The Ash of War, when applied to melee armaments (excluding whips), bestows the Heavy affinity and introduces the skill:

"Cragblade: A technique that harnesses the power of gravity. Embed the armament in the ground, drawing forth rocks from the earth to fortify it. This enhances attack potency and facilitates breaking through the defenses of adversaries."

These war ashes can be found on the elevated terrain west of the Unbreakable Bridge in Gelid.

To obtain these battle ashes, engage and defeat the dung beetle positioned in the corner of the area.