Forceful

Source Core Rulebook pg. 282
This weapon becomes more dangerous as you build momentum. When you attack with it more than once on your turn, the second attack gains a circumstance bonus to damage equal to the number of weapon damage dice, and each subsequent attack gains a circumstance bonus to damage equal to double the number of weapon damage dice.

Monk Unarmed Attacks

Falling Stone

Weapons

Elven Curve Blade, Falchion, Glaive, Orc Necksplitter, Scimitar