Fiend Pact doing both fire and acid damage?

[PrinceMyshkin]

I usually use GOO pact, but since my Sun Elf already had a combustion boost, I decided to LR and use Fiend. Now my attacks are doing acid, fire, and force damage. Fire SP is 136, Acid SP is 53 yet often the acid damage is higher than the fire damage. Both are higher than the force damage which is 90ish. Is this WAI and some game mechanic I'm not aware of, or what?

Edit: Can't delete. Never mind. I just realized I got the Earth Affinity buff in Steelstar's room. Duh!