Dude! This is epic beyond epic! And you did her eye-color correctly. It's a grayish blue and that's what you did! I like the background and the pointyness of her weapon--- Ah! Everything is so perfect! Especially her facial expression.
BTW, which reference were you using? There is a whole website dedicated to her with a zillion reference pics from the artbooks! xD [link]
Hahahah, I asked if you could submit it to the Riviera fanclub. I think people there would appreciate your drawing as well.