I've only just acquired the charm, but decided not to equip it.

I've basically got:
-Moderate healing on killing enemy (swab out to healing while out of combat when I'm out of combat).
-Increase Stagger Damage.
-Moderate Melee Damage.
-Moderate Melee Damage.
-Moderate Health and Melee Damage
-25% Resolve Gains.

This was my fight with Kojiro that I replayed. Winning fight was at final minute or so. My first win against him was essentially the same except my Skill Spam happened at the beginning rather than at the end.