SpoilerBab: 15 (Full attack 15/10/5)
Sneak Attack: 10d6(12d6 when on Assassin Stance, which should be always)
Lets assume the following ability scores:
STR:14 Dex:16 (+4 from levels) CON:14 INT:10 WIS:10 CHA:10
Slice is a Human, meaning he has no ability adjustment, gains extra skill points and an extra feat.
Human Bonus: Two Weapon Fighting
First Level: Mage Slayer
3rd Level: Weapon Finesse
6th Level: Blind Fighting (In place of Special Ability)
9th Level: Improved Two Weapon Fighting
10th Level: Crippling Strike
12th Level:Shadow Blade Technique
13th: Craven (In place of rogue special ability)
15th: Greater Two Weapon Fighting
16th: Staggering Strike (In place of rogue special ability)
18th: Pierce Magical Concealment
19th: Dark Stalker (In place of rogue special)
Stances Known: Assassin Stance (Swordsage level was delayed to get this stance due to non initiator's class counting as half initiator levels)
Cloak of Deception (Boost)
Sudden Leap (Boost)
Wolf Fang Strike (Strike)
Any other 2 you can learn
Skills (Total of 207 skill points to use):
Balance: 5; Climb: 10; Disable Device: 23; Escape Artist: 23, Hide: 14; Move Silently: 14; Open Lock: 23; Search 23; Use Magic Device: 19; Spot: 23; Tumbe: 23; Spellcraft:2.
That is 187 Ranks used. He does most everything you expect a rogue to do, he is a bit distracted towards what people are saying, but nobody is perfect, right? You could spend the rest on knowledge skill and sleight of hand, if you want to pick pockets for fun.
He is also not maxed on some skills, that is because he found out the wonders of magic items, and became reliant on them to improve some of them, neglecting his training there.
Lets assume, for this excercise, you don't, and get some skill tricks instead:
8 Ranks Used: Acrobatic Backstep (If you tumble behind an oponent, you make him flat footed, fixed DC 25), Clarity of Vision (You can see invisible enemies for 1 round as a swift action), Easy Escape, Escape Attack (Bonus to escape grapples, and a free attack when you escape a grapple, where the foe is flat footed, must use a Light weapon(Daggers anyone?)).
Now, one does not become such a good Rogue without obtaining some wonderful loot, right? Lets check out some of the gear Slicey carries with him now.
Equipment and Weapons to Slice mostly everything:
SpoilerHe is allowed to spend 760k gold according to the WBL.
First and foremost: Collar of Continuous Umbral Metamorphosis (22k) - Hide in Plain Sight, Darkvision, minor Resistance to Cold, Superior Low Light Vision, a speed bonus and a racial bonus to Hide and Move Silently? And this thing was in the bargain bin because?
Armor: Mithral Breastplate + 5 (Slick, Shadow, Silent Moves, Called) - 76,350 gp. Not the best protection money can offer, but if you aren't wearing it, you can call it, and it makes you stealthier. Study your marks first to improve it with appropriate energy resistance.
Weapon: +1 Eager Transmuting Colision Daggers of Deadly Precision - 98,302 each (x2)
Manuals Granting +4 Dex - 110,000
Gloves of Dexterity +6 - 36,000
Feathered Wings graft (flight speed = 2x Land speed) -10,000
Wand of Divine Power - 21k; Each charge lasts for 7 rounds, 2 more than your typical combat.
Tiger Claw Bracers(Pouncing Charge) - Charge and full attack for 15,000. I love Magi-O-Mart bargain bins!
We still got some gold to spend, so:
Scabbard of Greater Magic Weapon (2): Once per day, when drawing your weapon from this, you can activate the effect of the spell Greater Magic Weapon(CL 20) upon it. - (20(CL)*3(Spell Level)*2000(Use Activated)/5 (1 use per day) *1.5 = 36k each, lets call it 48k instead, because 36k is dirty cheap, considering the spells will last 20h unless dispelled.
Scroll of Contingency and Greater Heroism (2x1650 gold +1500gold for the focus) = 4800
Boots of Speed - 12k
Dorje of Offensive Precognition At 17th Manifester level (+6 insight bonus to Attack)- 114,750
If I didn't mess up anywhere: Remaining gold 93,496. Go buy yourself a house or something.
SpoilerNow, this is what we have been waiting for, isn't it?
Stats after gearing:
STR:20 (14+6 Divine Power) Dex:30 (16 +4 from levels +4 Tome + 6 Manual) CON:14 INT:10 WIS:10 CHA:10
BAB: 20 (Divine Power)
Init: 13 (+10 Dex +1 Sword Sage +2 Eager Enchant)
Either Dagger: 44(20+5 Enhacement Bonus + 10 Dex -2 TWF + 4Morale +1 Unnamed(Haste)+6 insight)/39/34/(29 MH Only)
MH: 1d4+5(STR)+10Dex +5(Enhacement Bonus)+5 (Colision)+13d6 +20 (Craven) Sneak Attack
OH: 1d4+2(STR)+10Dex +5(Enhacement Bonus)+5 (Colision) +13d6 +20 (Craven) Sneak Attack
Now kind sir who loves rogues... I beg of you... Please make me a 1 weapon fighting rogue that can hit dragons as many times per round as mine, for the same ammount of damage.
Other than damage and ability to hit a chosen foe, you can play however you like, so long as you remain a rogue, with at most a level dip in other classes for some usefull ability. You can outfit him to the best WBL can offer. I will admit to using a custom item, the scabbard one, feel free to use them too. Only restriction: Avoid obscure bonuses (a stone that gives +x to competence, insight, morale, luck and etc all day), I used those, but all come from a core source that can be easily traced (and dispelled).
The challenge is on, show me how TWF is bad for a rogue.
As you did say, if you don't hit... damage is 0, but hitting is a function that you have to properly prepare and customize for. This guy can easily slash trought dragon scales... He can TANK the Tarrasque, given that its not immune to the staggered condition, he will take damage, but its not gonna be one shot by the big T. Since he has quite a few ways to make his opponent flat footed every round, I doubt sneak attacking will be an issue without outright immunity, and given how much money he was left with, buying wands of gravestrike, golemstrike and vinestrike is not an issue.
On topic: My somewhat optimized rogue above, shows why TWF first feat is an 8 I guess, its follow ups are only cheaper because they are feat taxes.
Finally, I'll try to list up the feats on Complete Adventurer tomorrow sonofzeal.
Edit: Oh yeah, the reason Staggering Strike is on the build is to make moot your point on counterfull attacks. Good luck pulling those of with either a standard or a move action. I'll concede this guy might suffer if he fights a caster. If he is seen, that is.