Polymorphic
Melee weapons with the polymorphic weapon special property are made of a multitude of linked scales that can be reconfigured with a gesture. The wielder can cause the scales to flatten, form several contiguous sharp edges, or stand upright as a series of points. As a swift action or once as part of a full action, a creature wielding a polymorphic weapon can change its damage type from bludgeoning, slashing, or piercing to another of those types.
Source
Dawn of Flame: Sun Divers pg. 44