Start with a weapon whose requirements you meet and moves you like. An Ash of War can change the skill on a compatible weapon; an affinity changes its damage and scaling. Compare the resulting numbers with your own attributes before choosing: a higher scaling letter alone does not guarantee more damage.
Start with a weapon whose requirements you meet and moves you like. An Ash of War can change the skill on a compatible weapon; an affinity changes its damage and scaling. Compare the resulting numbers with your own attributes before choosing: a higher scaling letter alone does not guarantee more damage.
Read the weapon screen
First check the required Strength and Dexterity, plus any other listed attributes. The scaling section shows which attributes contribute bonus damage, generally graded from E through S; the attack power display combines base and attribute-related values. Raising an attribute the weapon scales with can increase its damage, but base damage, upgrades and the target's defenses also matter.
For example, if a sword needs more Dexterity than you have, meet its requirement before deciding whether its scaling suits you. Upgrade level changes the comparison too: compare options on the same weapon and upgrade level using your current stats.
Unlock the menu
In Gatefront Ruins in Limgrave, find the stairs down to a cellar and open the chest for the Whetstone Knife and Storm Stomp Ash of War. Rest at a Site of Grace and open the Ashes of War menu. Select a compatible weapon, then an available Ash and affinity; preview the attack power and confirm only after comparing. You can revisit the menu and change the setup later.
Not every weapon accepts interchangeable Ashes, and each Ash has weapon-type restrictions. If your weapon or skill is missing from the menu, check compatibility first. Additional whetblades unlock further affinity choices; an option not shown now may require another whetblade or a compatible Ash.
A practical comparison
On a compatible weapon, Standard retains its normal affinity. Once available, Heavy generally favors Strength, Keen favors Dexterity, and Quality balances the two. For a Strength-focused character, preview Standard and Heavy with the same weapon and compare the displayed damage; for a Dexterity-focused character, compare Standard and Keen. Don't assume either option wins at every level.
Some affinities split damage between physical and elemental types or add status effects. The total shown on the weapon screen is useful for comparison, but different enemy defenses can change real results. Test against the enemy giving you trouble, and remember that a useful skill or moveset can matter as much as a small number difference.
Sources: Bandai Namco combat guide, Whetstone Knife community wiki, Ash and affinity community reference.