1. The hands look really weird, the fingers almost look decent but he doesn't have any thumbs.
2. The cracks on his face are waaaaaaaaay to light to appear in anything but the unwrap, you need to add more contrast to those for them to show up at all in-game.
3. with the relative lack of any fine details save a few places with gold twirls, the texture could be re-sized to 128X128 (or any smaller dimension than 256x25) and loose little to no detail, while taking up 1/4 the file size. If you want to keep the current dimensions add some sort of textural detail, such as the cracks on the face, on the entire body. Considering this is a boss skin, details that would be impossible to see in some skins at least have a chance to be seen on this skin. But right now it looks sort of bland :/
4. Considering you are already making use of the abomination model for other units, this one is an imported model, so you might want to get a modeler to fix a few details, such as how the mouth interacts with the face-guard the skin has now. Right now the mouth looks a little awkward.
Anyways, looks cool so far, just keep working on it and making it better
