Your blade is keen enough to hew incorporeal creatures.
Benefit(s): As a swift action, you can imbue a weapon you wield with spiritual energies for 1 round. An imbued weapon damages incorporeal creatures as though it were magical. If the imbued weapon has an enhancement bonus of +2 or greater, it functions as a ghost touch weapon.
Pathfinder Player Companion: Haunted Heroes Handbook © 2016, Paizo Inc.; Authors: Alexander Augunas, Thurston Hillman, Isabelle Lee, Stephen Rowe, and Christopher Wasko.