From Pathfinder Lost Omens Character Guide, which isn't enabled.

Serrating

ITEM 10

Price 1000 gp

Usage held in 1 hand

Bulk —

A serrating weapon's bladed edge separates into jagged, swirling shards that spin along the blade. When dealing slashing damage, the weapon deals an additional 1d4 damage.

Activate Interact

Effect You brandish the weapon and focus its power, causing the serrated shards to buzz as they spin at a dizzying speed. On your next hit with the weapon this turn that deals slashing damage, the serrating rune adds an additional 1d12 damage instead of the additional 1d4 damage, and then the shards return to their usual speed.

Pathfinder Lost Omens Character GuideOGL