Deadly

Source Core Rulebook pg. 282
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.

Weapons

Composite Longbow, Composite Shortbow, Filcher's Fork, Glaive, Katana, Katar, Lance, Longbow, Ogre Hook, Rapier, Scythe, Shortbow, Starknife