You can charge up a weapon with this special property as a move action. When you do, you increase the weapon’s damage by the listed amount on the next attack you make with the weapon. Boosting expends charges from the weapon equal to its usage value. This increases the weapon’s damage and is multiplied on a critical hit. Boosting a weapon more than once before firing it doesn’t have any extra effect, and the extra charge dissipates if the weapon is not fired by the end of your next turn.