I also agree, WarCraft III does shading on its own, you might just want to add highlights slightly. The main thing which WarCraft III doesn't do is texture, try to put a leather kind of texture in it somehow, and/or some studs. Be Creative with the texture, not the shadowing/highlights (unless you want some parts to look higher than others on the leather or what not, just don't bother with shading it like it were in a photo).
Here are some leathers I've found through google image search, these might give you 1ideas... in fact, you could import them and use them as bevel textures or what not. Or if you want to be artistic, use it as a guide and try to imitate it (might not look as good but hell you made it and you deserve to be proud of it). There are so many possibilities, just experiment and see what works best for you. I reccomend you practice your art skills by trying to copy one of the images, just my personal opinion.
