Turner's Mercurial Armory

You slip a drop of liquid metal into the palm of a willing creature's hand. For the duration the creature can use a reaction to transmute the metal into a weapon with which they are proficient. This weapon can not have the ammo property, but may have the ranged property. In addition on a hit the weapon deals 1 additional damage die, dealing force damage. This uses the weapon's damage die, not any additional damage die, such as those from the sneak attack feature.