I didn't get a chance earlier to talk to your other points.
I like the armor changes. I wonder if it would be better to raise the heavy armor to a 2 value, but keep them as a 2 body slot item. The light armor could be separated to a shield w/ armor value 1 and 1 paw and the armor as 1 armor slot and 1 body slot. This would allow a light armored mouse with two light weapons, or a bow and quiver. Or a super tanky mouse, heavy armor and shield, medium or light weapon.
I would like to know about the supplement part as well, I want to add more to the beasts, like beetles, ants, bees, wasps, moles, squirrels, chipmunks, weasels etc.


So what I've decided is that the shield and Helm roll their usage die immediately and prevent damage and take a usage only on a 4+. So if you are wearing all three and you take 5 points of damage you roll a die for your shield and a die for your helm. Lets say you get a 5 for the shield and a 2 for the helm. Your shield takes one point of usage and you take 3 damaged (5 - 1 armour - 1 shield). The armor only takes usage damage at the end of combat, and as before you can sacrifice your shield at any time after finding out the result of an attack to cancel it entirely.