these are the damage classes...

these are the damage classes in my game:

Physical:
-Slash
-Pierce
-Blunt

Elemental:
-Fire
-Frost
-Lightning
-Nature

Magical:
-Arcane
-Holy
-Shadow
-Necrotic 

All of those have a resistance for it

A weapon or spell can have multiple damage class
and a character can have multiple resistances