Source Core Rulebook pg. 282 4.0
On a critical hit, the weapon adds a weapon damage die of the listed size. Roll this after doubling the weapon's damage. This increases to two dice if the weapon has a greater striking rune and three dice if the weapon has a major striking rune. For instance, a rapier with a greater striking rune deals 2d8 extra piercing damage on a critical hit. An ability that changes the size of the weapon's normal damage dice doesn't change the size of its deadly die.

Monk Unarmed Attacks

Cobra Fang


Bow Staff, Claw Blade, Composite Longbow, Composite Shortbow, Elven Branched Spear, Fangwire, Fauchard, Fighting Fan, Filcher's Fork, Forked Bipod, Gakgung, Glaive, Hongali Hornbow, Kalis, Katana, Katar, Kris, Lance, Longbow, Machete, Mambele, Naginata, Nodachi, Ogre Hook, Pantograph Gauntlet, Rapier, Rapier Pistol, Rhoka Sword, Scythe, Shauth Blade, Shauth Lash, Shears, Shield Bow, Shortbow, Starknife, Tamchal Chakram, Taw Launcher, Three-Section Naginata, Urumi, Wakizashi, War Lance, War Razor, Zulfikar