I think it has to be the weapon you're using. I mean : no way you gain benefits of your ring focus while using a standard blade (or it would be a way of having a less easily lost focus but applying it to a more powerfull weapon, even to many weapons).
You have to punch your opponent with the ring to gain these benefits.
So a ring seems okay, a jewelry on horns can apply, a earring or an amulet, it'll be a little bit hard.