pf2e.fyi
From Pathfinder #163: Ruins of Gauntlight, which isn't enabled.

Ghost Strike

FEAT 6
Activity 2 actions
Archetype Ghost Hunter

Once per day, you can infuse a weapon you are carrying with magical energies that allow it to strike true against incorporeal undead. The weapon gains the effects of the ghost touch property rune for 10 minutes. At 10th level, you can apply this effect to two weapons instead of one.

Pathfinder #163: Ruins of GauntlightOGL