Got a Real-World Weapon, Armor or Tactics Question? Mk. XXI

[snowblizz]

So while I was making a grueling drive across the country, I got to wondering about how roads were built and maintained in the far past, and how thry may have differed between regions/cultures, as well as how this would effect troop movement.

I imagine a lot of roads start out as well worn paths that many people travel, did many of them remain just dirt pathways, or was there more to it than that?

Generally roads weren't maintainted much in the faux medieval period. Until fairly late the best roadengineers in Europe was the Romans and their roads was all that anyone really had. That we'd recognize as roads anyway. And almost all major medieaval roads followed, were built on or just was the Romand roads.

Also generally roadmaintenance tended to fall upon those living along the road, as it is in many places still, even in developed countries the owner of a building might be responsible for the sidewalk even though such things tend to fall

Still generally the more people were around the "better" the road, and more likely to have an attempted pavement. So towns could ahve paved roads sort of "fading off" as we are removed from their area of influence.

Majorally speaking major features such as bridges were more likely to be maintained in a more systematic capacity, so various bridge and road tolls have ancient pedigree. Could even be the nucleous for a society. And often might be the responsability of a local potentate of some kind.

Yes differing regions would have vastly different roadnetworks, geography determines a lot. Which is why "road" in Scandinavia meant a beaten path through the forest you barely got a horse through except in winter when you used the frozen rivers. Until like the 1800s.

Sergeantilly roads, where not made by the Romans pretty much, would be a snaking path of local roads, with the main feature being a marker telling you how far you are (a major development). You start broadening that, and trying to cut out a better path, removing rocks and perhaps try to avoid the worst places.

Unsurprisingly this has a major impact on troop moments, where many places in the interior of Scandinavia e.g. it was a firm "nope" (not impossible, but it was a good way to get rid of your army). But it varies a lot, smaller forces more lightly armed could move much easier through broken and roadless country on paths. Anyone used to having good roads were at a disadvantage in suhc conditions, wheras ofc the opposite was true in "open country" where the more organised army can bring more force to bear. Romans and the Germanic tribes, obviously.

[Tobtor]

Generally roads weren't maintainted much in the faux medieval period. Until fairly late the best roadengineers in Europe was the Romans and their roads was all that anyone really had. That we'd recognize as roads anyway. And almost all major medieaval roads followed, were built on or just was the Romand roads

This is true, though the perspective is of course Scandinavian, but the roads of Northern Germany, England and France wasnt (on average) much better. Of course paved roads existed, but they were rare, and mainly in and around towns, or between two closely placed towns.

I have excavated several roads (though thier date is very hard to determin...), and basically they consist of a set of wheel tracks cutting deeper and deeper into the ground, until the carts cant drive there, and they are moved a some distance to either side. Some of the better roads do sometimes have one or two ditches for drainage though (at least from the 16th century, but quite possibly also before), that the locals had to maintain.

Bridges are of course built and maintained and are important (as snowblizz say), and sometimes the road might be paved close to the bridge to accommodate the heavy traffic. Then some hundred meters away the road would branch out to several smaller roads which might not be paved. We have such patches of paved roads going back to at least the Iron Age in Scandinavia.

Other possibilities are timber built roads, or roads reinfoced when crossing wetlands etc (very common in the Netherlands and Denmark, some of the Netherlands ones are quite decent).

Of course the extensive Roman road network was maintained in some places, and even expanded in some areas during the medieval. How well they were maintained is hard to tell. I have also seen decent roads from ancient china... So I expect it to depend on your sense of period, and organisation in the respective area.

[Asmodean_]

Scimitars.

Why?

Why not just a regular straight blade that'd be (presumably) easier to make?

[Max_Killjoy]

Scimitars.

Why?

Why not just a regular straight blade that'd be (presumably) easier to make?

A curved blade makes draw and push cuts easier and more efficient.

[Hoosigander]

What I write is specific to Early Medieval Ireland, since that's what I know best. It is also somewhat abstract since it is based mainly on law tracts. In Ireland there were multiple categories of road: a slige which had to be wide enough for two chariots to pass each other easily, a rout wide enough for one chariot and two horsemen, a lámraite a small road which connected two larger ones, a tógraite a road which was rented by a private individual who could collect tolls from travelers, and a bóthar or "Cow Road" which had to be as wide as two cows.

The larger roads were by law built of branches, stones, and earth. The story Tochmarc Étaíne describes the hero Midir building a road through a bog as a result of a wager, he lays down tree trunks and covers it with gravel and stones. The roads were supposed to be maintained by the local king and to be renovated every winter, before fairs, and during war. If a traveler was injured on the road it was the local king who had to pay compensation.

Natural features can also be incorporated into traveling routes. The Riada Esker in Ireland is a system of ridges formed by sand, gravel, and rocks deposited by meltwaters flowing underneath a glacier. The Riada Esker was called the "Great Way" and connected the West and East coasts.

In prehistory, there are remnants of Iron Age trackways that have been found in Ireland. Many are made from woven hurdles laid on brushwood, but there are some built of split planks that could accommodate wheeled vehicles. The most famous of these constructions is the Corlea Trackway dated to 148-147 B.C.

Spoiler: Corlea Trackway Images

Show

[BayardSPSR]

In Ireland there were multiple categories of road: a slige which had to be wide enough for two chariots to pass each other easily, a rout wide enough for one chariot and two horsemen, a lámraite a small road which connected two larger ones, a tógraite a road which was rented by a private individual who could collect tolls from travelers, and a bóthar or "Cow Road" which had to be as wide as two cows.

For context, how wide were the chariots in use at the time?

[Max_Killjoy]

For context, how wide were the chariots in use at the time?

Roughly 6 feet.

[Galloglaich]

Question: in the context of a modern army, what sort of impacts will you see from progressively worsening morale?

Presumably, badly-motivated or even anti-war conscripts would pull down their units, but how strong would this effect likely be?

Additionally, what sort of measures would be taken to try and maintain fighting capability for as many troops as possible even as equipment begins to grow scarce?

Read up on the US Army in Vietnam during the 70's. That is about as bad as it gets. Pretty interesting too.

[Hoosigander]

For context, how wide were the chariots in use at the time?

Roughly 6 feet.

Max_Killjoy is correct, a chariot would be around six feet wide. However, it is important to note that estimate is based on evidence from British and Continental Celtic chariots. The evidence for chariots in Ireland are mentions in literary and legal sources and some depictions on High Crosses. Unfortunately, no one has found chariots deposited in graves like in Britain and Continental Europe, there is some archaeological evidence in the form of linchpins, but nothing as extensive as elsewhere.

Spoiler: Ahenny Cross

Show

Ahenny High Cross, 8th Century

[No brains]

I thought I once read that a really good punch should use the last two knuckles, on the ring and little fingers, as the point of contact. I'm not sure where I read this and I don't know if there's any reason for this to be true. Is it mechanically stronger to hit that way? The best reason I can think of for punching this way to to limit damage to the index and middle fingers, as those are used more often for fine manipulation.

[Brother Oni]

I thought I once read that a really good punch should use the last two knuckles, on the ring and little fingers, as the point of contact. I'm not sure where I read this and I don't know if there's any reason for this to be true. Is it mechanically stronger to hit that way? The best reason I can think of for punching this way to to limit damage to the index and middle fingers, as those are used more often for fine manipulation.

Depends on your punching technique.

If you punch a lot using a vertical fist (called a 'sun' fist in Chinese martial arts as the fist resembles the Chinese character for the sun 日), then contact with the last two knuckles is preferable due to body alignment and how the punch is thrown (usually from the elbow and along the 'centre line', but I can only say for the style I've studied).

If you punch a lot with the more regular horizontal fist, then the index and middle finger knuckles are better for the same reasons.

There's a fair amount of debate (ie angry internet raging) of which is better, but regardless of how you punch, you do have to condition (ie train) the appropriate knuckles to take the impact and make sure you have good technique.
When I was first starting out training, I cracked my ring finger knuckle and it took a couple years for it to heal fully (known as a Boxer's fracture).

[Khedrac]

Scimitars.

Why?

Why not just a regular straight blade that'd be (presumably) easier to make?

Think about a straight edge intersecting with a body.
Assuming a roughly cylindrical body and a horizontal cut the blade should impact as the tangent to the surface which helps greatly with damage efficiency.
Problem - yes it impacts as a tangent, but it probably isn't the bit you were aiming for. To get a straight edge to hit the exact spot you want means you have to come in at a very, very specific angle. Given armour etc., this actually makes the cutting sword not that efficient.
Now consider the curved edge hitting the cylinder (the scimitar or sabre).
Although the blade cannot be said to form the tangent to the cylinder, the blade's tangent will be the cylinder's (body's) tangent at the point of intersection - still and efficient way of cutting.
However, hitting the part of the cylinder you want is now much easier - hitting with a different part of the blade hits a different part of the cylinder from the same striking angle - you have more options to achieve the hit you want.

Now whilst a cylinder is a good approximation in some cases, it is poor one in others.
Try hitting a flat surface: The straight edge hits at an angle - pretty much guaranteed (OK it is fine for hitting the corners).
The curved edge still hits with its tangent being the flat surface (up to the limit of curvature).

As Max_killjoy said above, the scimitar is far more efficient for cutting that a straight edge in combat.

(In a kitchen one is trying to do very different things, but look at old carving knives - curved edge. Also look at the cutters used to section pizza - curved edge.)

[Carl]

Also look at the cutters used to section pizza - curved edge.

Appeal to pizza, thats a new one.

Sorry i now it's true, but having it pointed out is funny somehow.

[Max_Killjoy]

As Max_killjoy said above, the scimitar is far more efficient for cutting that a straight edge in combat.

To follow up on my earlier comment, this is because a sword or knife edge does not just push through what it's cutting -- it has to slide along the surface to some degree. A curved blade more naturally falls into a push or pull of the blade across the surface of the target as a part of the swinging or even thrusting motion.

[warty goblin]

Scimitars.

Why?

Why not just a regular straight blade that'd be (presumably) easier to make?

Note also that a curved blade is not necessarily any more difficult to make. One way to define the edge geometry of a sword is to forge the edge bevels in with a hammer prior to grinding and polishing the blade. Beveling in this manner does not remove any material from the blade, so since you are taking the same amount of material and making it thinner, it will to curve the blade, with the beveled edge on the outside of the curve. Forging in the bevel of a single edge blade in other words naturally gives you a curved sword. If you watch a smith bevel a double edged sword , they alternate which side of the blade they're working, in order to keep the piece straight.

[No brains]

Depends on your punching technique.

If you punch a lot using a vertical fist (called a 'sun' fist in Chinese martial arts as the fist resembles the Chinese character for the sun 日), then contact with the last two knuckles is preferable due to body alignment and how the punch is thrown (usually from the elbow and along the 'centre line', but I can only say for the style I've studied).

If you punch a lot with the more regular horizontal fist, then the index and middle finger knuckles are better for the same reasons.

There's a fair amount of debate (ie angry internet raging) of which is better, but regardless of how you punch, you do have to condition (ie train) the appropriate knuckles to take the impact and make sure you have good technique.
When I was first starting out training, I cracked my ring finger knuckle and it took a couple years for it to heal fully (known as a Boxer's fracture).

Thank you for the information. How does one condition bones like that? Does every bone along the arm need to get conditioned or just the striking bones?

Appeal to pizza, thats a new one.

Sorry i now it's true, but having it pointed out is funny somehow.

Appeal to pizza is my favorite logical fallacy and I always fall for it when there's real pizza involved.

[Brother Oni]

Thank you for the information. How does one condition bones like that? Does every bone along the arm need to get conditioned or just the striking bones?

The same way you condition any part of your body, painfully.

More seriously, hitting things hard enough repeatedly will cause damage to the structures involved - as that inescapable SOB Newton said, for every action, there is an equal and opposite reaction, so if you're hitting things at 1.5kN, that 1.5kN is also being applied back into your body. In the case of punching, it causes micro fractures in the bones, primarily in the metacarpals but the stresses involved will also slightly damage the rest of the muscles involved (arm, core, shoulder, etc), the tendons connecting the muscles, the bone where those tendons attach, the joints, etc. With proper rest and diet, the body will heal the damage, making the repaired structures stronger, thus allowing you to punch harder, which damages the body again, etc.

The repeated impacts to the knuckles also tends to make them more prominent - if you look at a fighter's hands, you can see how they tend to land their punches (in my case, it's the index, middle and ring fingers as I'm quite fond of the backfist punch). I've heard of Muay Thai practioners help their shin bone conditioning by initially rolling a glass bottle over the shin then progressing to rougher and harder materials inbetween their training sessions.

If you meant the actual biological processes of how the body repairs such damage, I can go into the detail of that but detailing how the bone repairs itself via fibroblasts forming a callus and the subsequent mineralisation and ossification process is probably something for another thread.

[Tiktakkat]

Depends on your punching technique.

If you punch a lot using a vertical fist (called a 'sun' fist in Chinese martial arts as the fist resembles the Chinese character for the sun 日), then contact with the last two knuckles is preferable due to body alignment and how the punch is thrown (usually from the elbow and along the 'centre line', but I can only say for the style I've studied).

If you punch a lot with the more regular horizontal fist, then the index and middle finger knuckles are better for the same reasons.

I punch using the vertical fist, and I've always been taught, and experienced, that contact with the first two knuckles is preferable, due to both alignment with the elbow and to avoid a boxer's fracture.
I'm not really sure how you could or would use the last two knuckles to achieve any sort of useful alignment.

As for comparisons with the horizontal fist, there is a question as to whether that is intended as a "safety punch" to prevent proper alignment of the knuckles with the solar plexus and other targets.
From that, there are questions as to the differences between the alignment at the start of the movement and impact, during the impact, and at the end of the impact. a "vertical" punch might be intended to impact at a 10-20 angle off of vertical for best fit under the rib cage for strikes to the heart and liver as well as the solar plexus, while the "horizontal" punch represents the final position after a strike to other muscle groups that began vertical but twisted on impact to aggravate the damage to the muscle.

And then of course there are issues regarding the difference between bare hand strikes and covered (with boxing gloves or the like) strikes. Those pads are to protect the striking hand, not the target, typically the face. With bare handed strikes, the face tends to be a terrible target because of the structure of the skull. Even a "proper" punch is liable to result in a broken hand. Conversely, strikes to the rib cage, particularly at muscle/cartilage attachment points, generally do less damage to the striking hand.

The same way you condition any part of your body, painfully.

This.

Big time.

Due to damage to my wrists I avoid punching as much as possible. Despite that, I still have considerable visible scarring on the knuckles of the index and middle finger of both hands.
For other strikes, I did considerable conditioning of my finger tips, palm heels, and back of my wrist. (The last of which likely contributed to the wrist damage making punching less of an option for me.) I hit bags, pads, wood, drywall, and eventually even cinderblocks with finger tips.
I also conditioned my shins on heavy bags, including kicking the bottom of an old one with all the sand settled, and conditioning my big toe by striking up to drywall.

I will note though, that you must be EXTREMELY careful with such conditioning or the damage will eventually become debilitating.
All the macho factor of being able to clash shins with someone and watch them drop whimpering while you stand around smirking when you are in your 20s is really not worth all the limping when the air pressure changes too rapidly when you are in your 40s.

[Galloglaich]

Max_Killjoy is correct, a chariot would be around six feet wide. However, it is important to note that estimate is based on evidence from British and Continental Celtic chariots. The evidence for chariots in Ireland are mentions in literary and legal sources and some depictions on High Crosses. Unfortunately, no one has found chariots deposited in graves like in Britain and Continental Europe, there is some archaeological evidence in the form of linchpins, but nothing as extensive as elsewhere.

Spoiler: Ahenny Cross

Show

Ahenny High Cross, 8th Century

Some of the Irish roads seem to follow a pattern of complex, well built, well surveyed roads in Continental Europe which predate the Romans. Some of these are associated with "Celtic" culture but that is such a loose term that it's hard to realistically associate with much any more (it's out of favor with Academics). Anyway some kind of Celtic or proto-Celtic (Halstadt or before) culture seems to have been pretty good at making some good roads.

There were major 'road' (trails, portages etc.) systems crisscrossing Europe which also pre-date the Romans but which the Romans updated and built settlements along. Notably among these



The Via Regia
The Via Imperii
The Via Lusatia
The Amber Road

The Silk Road also connects with the Via Regia.

The medieval tends to be more elusive in this as in with all other things. It is very hard to generalize. Many contradictory things are going on at the same time. But I can say that in the Late Medieval they did have some fairly sophisticated roads not necessarily inferior to what the Romans built. The Romans built roads of course for different purposes and with different techniques. The Romans for example relied heavily on slave labor whereas in the Late Medieval they relied much more on machines and skilled labor. The Roman roads were for moving large infantry formations (Legions) from one end of the Empire to the other, and they tended to be incredibly, almost pathologically strait. Medieval roads were more for trade though of course armies used them too. They tended more to follow the natural curvature of the terrain.


This is supposed to be a section of the old Via Regia

In the Holy Roman Empire there were a series of 'roads' (some of them were probably recognizable to us as roads, others more like trails, portages, traces etc.) which were called Reichsstraßen. Imperial streets is I think the literal translation. These had a special legal status as in robbing somebody on the Imperial road could get you in extra trouble, and certain types of other violent or destructive activities were more severely punished if they occurred on the Imperial roads. Similar rules were in effect in various countries for "Royal roads" or streets.

However in the Late Medieval period the most well maintained, built and surveyed roads were not the Royal or Imperial ones necessarily, but were the ones in the more built-up, urbanized areas. For example, the Old Salt Route which was actually part of the Via Imperii I think, started out as a simple trail or trace but was eventually built into a nice road by Lubeck and Hamburg. It was used for carting salt and needed to be in good repair and relatively immune to weather. I believe this section is the actual old medieval paved road:




Road systems in Northern Italy, Flanders, and around other smaller clusters of powerful or wealthy towns (for example in Upper Lusatia where a handful of towns formed the Lusatian League) tended to be well maintained. However in the middle ages for a variety of reasons, especially the fairly brisk trade of all kinds of bulk commodities and finished goods, they liked to move things by ship, boat or barge quite a bit. They made an incredible network of canals all over Europe. These again, started out mostly in the more urbanized areas. For example between Lubeck and Hamburg (and Luneburg and some other towns) the 7 mile Stecknitz Canal, finished in 1390, was one of the first large man-made canals made in Europe. Apparently they were moving about 30,000 tons of salt per year down that canal in the 15th Century, along with a lot of other cargo (and if necessary, troops and stuff like guns).

https://en.wikipedia.org/wiki/Stecknitz_Canal

Today there is an incredible network of these canals linking almost every river in Europe. Water was (and generally, still is I believe, even compared to rail) a much more energy efficient way to move heavy goods, and often in medieval times, a safer way to travel partly because you could carry lots of heavy guns with you.


Medieval road systems and other infrastructure like bridges, tunnels and passes, were sometimes paid for by tolls, sometimes paid by a prince but most often by the nearby towns who wanted them in place and well-maintained for their own commercial and military benefits. Roads which were part of or along the major trade routes like the Via Regia or the Amber Road were more likely to be better maintained by the local municipalities because they were usually steady sources of income.

One other feature of medieval roads in the more organized areas, is that many of them were used by postal systems, kind of like pony express systems. The original coach, the kind of personnel carriage you see portrayed so often in period films set in the 17th or 18th Century, got it's name from a town in Hungary which was one of the pony express postal stations.

https://en.wikipedia.org/wiki/Coach_(carriage)#History

https://en.wikipedia.org/wiki/Carriage#Coach
Of course the medieval period being complicated, there were also many areas with almost no improved roads at all.


G

[Galloglaich]

This is one of the locks from the canal I mentioned, apparently (according to the Wiki) it's the original medieval lock. Gives you an idea how sophisticated they were (though the canal was quite shallow, only deep enough for fairly small barges)




The Flemish and the Dutch were also famously very good at making tons of canals. Venice is also known for this...

Some of the canals in Northern Europe even have shade trees planted the whole way...

[Galloglaich]

A model of that same lock, the Palmschleuse at Lauenburg, meant to show what it looked like circa 1430

[Galloglaich]

Another old medieval road, the Via del Sale in Italy



https://www.theguardian.com/travel/2...alt-road-Italy

http://www.dangerousroads.org/europe...ale-italy.html

[Brother Oni]

I punch using the vertical fist, and I've always been taught, and experienced, that contact with the first two knuckles is preferable, due to both alignment with the elbow and to avoid a boxer's fracture.
I'm not really sure how you could or would use the last two knuckles to achieve any sort of useful alignment.

Could I ask what style you've trained in? I'm quite short and the relevant martial arts style I trained in (Southern Mantis) is basically designed for my height and body shape, so I use the vertical fist for punching upwards or to normal height on the average westerner .

[Roxxy]

Is there really much advantage to holding a knife with an icepick grip? Been messing around with a kitchen knife and moving boxes (yes, I know, not a scientific study or a combat weapon), and holding it blade down doesn't seem to give an increase in power, and it's harder to control where the blade goes. I feel like I can stab faster and closer to where I want just holding the blade up and stabbing forward. Does this match combat trained people's experience with knives?

[Max_Killjoy]

Is there really much advantage to holding a knife with an icepick grip? Been messing around with a kitchen knife and moving boxes (yes, I know, not a scientific study or a combat weapon), and holding it blade down doesn't seem to give an increase in power, and it's harder to control where the blade goes. I feel like I can stab faster and closer to where I want just holding the blade up and stabbing forward. Does this match combat trained people's experience with knives?

From what I've read, that "reverse grip" is used more for certain slashing techniques, and you'd really only stab down like that when you had an opponent helpless, and then you'd probably put your off hand on the back of our main hand to add extra control and power.

[BayardSPSR]

Read up on the US Army in Vietnam during the 70's. That is about as bad as it gets. Pretty interesting too.

The Soviet Army in Afghanistan might be another good example, but the material on it's a bit thinner on the ground. Or at least, you have to look harder to find it in English.

(For example, I've heard anecdotes of Soviet officers literally dueling each other over women with grenades, but those are understandably difficult to corroborate.)

[Tiktakkat]

Could I ask what style you've trained in? I'm quite short and the relevant martial arts style I trained in (Southern Mantis) is basically designed for my height and body shape, so I use the vertical fist for punching upwards or to normal height on the average westerner .

Isshin Ryu, an Okinawan system that is predominantly Shorin with a bit of Goju.
It is generally a punching/kicking range system, but because I'm on the short side (5'8") and squat (180-210 at prime fighting weight), I use it more at punching/grappling range, and do a lot more finger strikes instead of punches.

One thing I stress when teaching that is rather "heretical" (at least in my area) when discussing kata "bunkai" is that the difference in height is HIGHLY relevant to the technique used. A target that requires a "vertical" punch on someone of the same height will require an uppercut on someone taller and a down "horizontal" punch on someone smaller.
Well, unless you really like breaking your hand or flailing ineffectively.
That is one of many reasons why I phrase answers to most questions about techniques as "generally" - there are too many variables for absolute universal answers to be valid.

[Tiktakkat]

Is there really much advantage to holding a knife with an icepick grip? Been messing around with a kitchen knife and moving boxes (yes, I know, not a scientific study or a combat weapon), and holding it blade down doesn't seem to give an increase in power, and it's harder to control where the blade goes. I feel like I can stab faster and closer to where I want just holding the blade up and stabbing forward. Does this match combat trained people's experience with knives?

It depends on the knife and the target.

If you need to penetrate mail or plate armor, or a skull, the ice pick grip, sometimes referred to as the rondel grip from the weapon of that name, is essential. Which is pretty much why rondel's were constructed the way they were, and why the grip is named for it.

If you need to cut a throat or gut someone in street clothes, the natural or sword grip is going to be more effective.

The thing is, a rondel is almost a spike, and slashing with it is nearly useless. So you pretty much MUST use an ice pick grip with one.
Conversely, something like a machete is just a cleaver, and stabbing with it is significantly less effective. So you pretty much MUST use a natural grip with it.
Of course then you get things like a bowie knife which can hack AND slash with great force, so you may want to switch back and forth depending on what you are doing at a particular moment.

[Roxxy]

Would you ever want to slash with a knife, though, barring slitting a throat or the use of a cleaver like a kukri? I've been of the impression that yoj stab in a knife fight, and I feel like the sword grip is a lot easier to control with better reach.

[Mike_G]

Would you ever want to slash with a knife, though, barring slitting a throat or the use of a cleaver like a kukri? I've been of the impression that yoj stab in a knife fight, and I feel like the sword grip is a lot easier to control with better reach.

As with all things, it depends on a lot.

First, you need the right knife. Some knives don't slash well at all. And you need the right target. If you are fighting, not just walking up and shanking an unsuspecting guy, you might slash at his arms to disable his knife hand or stop him from grabbing you. His hands and arms are probably closer to you that his body, so you may not be able to stab him until you get past the arms, which might be holding a weapon, so trying to disable them first is something you might do.

A slash (with a big enough knife) is more likely to sever muscle or tendons and blood vessels than a stab, so on an arm, it's more likely to be disabling. It's less likely to reach organs if you slash at the body than if you stab.

All that said, people can take a lot of stabbing. There are lots of accounts of people being stabbed a ton of times before falling over, even if the wounds eventually prove fatal. Slashing the guy's weapon hand first might not be an awful idea.