Got a Real World Weapons or Armour Question? Mk XI

[Brother Oni]

I have a question about shield design. Were the majority of them angled to deflect attacks? Or a flat surface to just absorb the impact? I just wonder because it seems to me that it would be smarter to not force a guys shield arm to absorb the full weight of the impact, and even deflecting a bit of the force could mean the difference between a broken arm or a hale and hearty warrior ready to continue. But I recall seeing a lot of movies with different warrior groups and many of them seem to have flat surface shields. Is it that there is a danger of the blow sliding off the shield and hitting the guy behind it?

Depends on the shield really. A lot of shields are flat so they interlink together better, forming a shield wall (norman kite shields and viking round shields for example). Others are more curved to help deflect blows (Roman scutum and I remember a odd one, possibly celtic, which was effectively a 90 degree curve).

Shields generally aren't used statically though and can move to intercept or deflect blows, so it's not really just something for the opponent to practice his cutting/breaking skills on.

Generally shields have protrusions to reinforce their structure and stop weapons sliding around on the surface (the rim of the shield especially).

Large (and hence thin) shields may not stop crossbow bolts or arquebus bullets, but they would certainly be slowed. Not enough for lorica, I would expect, but if the pseudo-Legions used updated equipment such as plate, that should be enough to stop the slowed missiles most of the time.

A seriously doubt a Roman scutum would be effective in protecting against a medieval era military crossbow. When I have more time, I'll look up some values and crunch some numbers to figure out how much of an effect less than an inch of wood would have on stopping a bolt.
To clarify, when I say 'wouldn't be slowed down', I mean the bolt would penetrate through the shield and still significantly injure or incapacitate the person on the other side, to the point where it would be more effective for the person not to be encumbered by the shield.

An updated pavise style shield would be effective though, but we're moving away from your legionary concept.