Going with the whole monk idea, this is one class I'd like to see added. And I think it could still be original despite h2h specs/assassins already serving as semi monks.

The only weapon you'll ever learn is h2h, you will however gain some insight into other weapons to better defend against them, like that certain Paladin virtue. There are no kicks. No kicks.

Say, lev 10 - defend pierce. lev 15 - defend slash. lev 20 - defend blunt. etc.

As was stated earlier, monks would only get two attacks a round. For skills, here's a selection -
Improved Ironhands obviously. Parry, dodge. No shield.
Harden skin: Gives dam redux similar to stone skin. Lev 20+ ish. Also gives slight resistance against heat/cold.
Heightened senses: No assassin jive here. Gives a boost to dodge.
Ability to counter a bash with a throw. And don't start whining about 'waaah, they can't be lagged!' Use cranial or the dozen other laggers.
Immunity to throw assassin/h2h spec style.
And stray away from the ####ty oriental references littered all over the assassin class. There would be no dragon punch, etc. OWAZAAAAA!
Resistance/ability to cure poisons.
Dirt/blindness only gives half the hitroll penalty.
Badass ####: Bonus to defs when fighting multiple foes, possibility to add confuse for x number of hours to opponents affects.
Channel spirit: Area or single foe mental attack.
Weaken weapon: Succesfully parrying a weapon with your hands, you use your 'spirit' to weaken it (lower avg dam for a duration).
Identify potion, and only potion.

Monks should always be neutral. For races, how about - Human, cloud giant, gnome and svirf.

Another possibility would be to simply split the assassin class into two sub classes, removing some skills, adding a few new ones. Whatever.