The lineart is very clean so its all about the coloring on this. It appears that it will look good, judging by the hat. I would make sure that regardless of colors chosen, the eyes remain as visible as they are in this stage. Unaware what a ff9 blackmage is, I don't like the *wing* and would explore turning it into a flowing cape or something else.

I also think the wing could be changed a little, either push it back and up to bring out the full glory. Or have it folded back. Right now it sort of seems in between those two positions.

Because he doesn't have the same outfit of the good black mages, I asume it's a Black Waltz. If I recall correctly, their wings were more..mm how can explain it, not so angel like, they were more ragged and dark. But since this is only inspired, I guess you can make your own wings (remember to put two of them, unless it's Sephiroth Waltz). I look forward to see this shaded.