How about a cow patterned dress instead of skin? Main reason being the spots look like birthmarks or injuries, rather then spots, to me at least; also, with how much & large they are, makes it look gross -- jut google scabs and you'll feel the same way :p
Mind control is how I understood the power in game. Making enemy's thoughts sluggish and your allies think they are better, ignoring pain and such (it's why he heals for so little)So a cow patterned dress, gloves and the horns on a headband would fit the theme better. A cowbell necklace to, unless accessories would be to difficult then a color swap. But this is your game, so go with what you want.
Actually, your character's gift is just control in general. The Boost spell works via body control which is why it is Physical magic instead of Support magic. That spell is also what allows you to make Val's breasts and hips larger if you make her a bimbo. I have though made some changes to the avatar and posted them, if you want to take a look and see what you think of it.
I think the form could use a few more cow features (tail, muzzle, ears, etc), but I understand if that's too much trouble changing things for just one character.