This Ash of War grants an armament the Occult affinity and the following skill:

"White Shadow's Lure: Hold armament in a brief, silent prayer to create a white shadow. The apparition lures in foes of human build who are not in combat, drawing their aggression. Effective on demi-humans even if they are already in a combat state."

Usable on all melee armaments.

The ashes are located in the Volcanic Mansion of Gemmel Volcano, which needs to be obtained by completing side quests.

First talk to Tanis, the hostess of the mansion, to get the room key.

Use the key to open the door of the restaurant and get a letter from the volcano mansion on the dining table.

Then go to the north of the ruined house of the warriors of Ningmgfu and destroy the ancient knight Ishutuo.

Then go back to the restaurant of the volcano mansion and talk to Bernal, and you can get the battle ash for 6500 runes.

 Bernal