Whetstone Knife

Whetstone Knife is a key item in.

Description

 * Whetstone with a cipher inscription, made to look like a small knifeblade.
 * Allows the use of ashes of war at a site of grace to bestow new battle arts and affinities to armaments as skills.
 * The battle arts and affinities will depend on the ashes of war used.

Acquisition
It's found at Gatefront Ruins, in the cellar's chest, alongside the Ash of War: Storm Stomp.