Iomedae's Sword Feat 6

You've trained to fight the ancient enemies of lost Golarion. When you deal damage to a demon, devil, dragon, or undead with a weapon, you deal persistent spirit damage with the holy trait equal to the number of weapon damage dice. When you deal damage to one of these creatures with a spell cast from a spell slot that does not have a duration, you deal persistent spirit damage with the holy trait equal to the spell's rank.