The Ash of War provides a weapon with the Keen affinity and imparts the skill "Spinning Slash."

Skill Description: Spinning Slash - A technique favored by agile warriors. Cut down adversaries as your body rotates. Additional input enables a subsequent attack.

Applicable to swords, axes, and polearms (excluding colossal weapons).

The war ashes can be found within the dilapidated abode of the warriors of Nimgfu.

Acquire this Ash from  Bernal by expending 1200 runes for its purchase.