Gunfighting
Reroll a 1 on a damage die for attacks with gunpowder weapons.
When you roll a 1 on a damage die for an attack you make with a weapon with the gunpowder property, you can reroll the die and must use the new roll, even if the new roll is a 1. The weapon must have the gunpowder property for you to gain this benefit.
Source and licence
From Tome of Heroes.
Licence: Open Game Content (OGL 1.0a).