Agent York

Shiny just means that they are a different color, like "they're shiny and new" I think. I have a shiny Glaceon, and he's a much paler blue than a normal one. I've seen someone with a gold Altaria, and their normal color is blue. Shinies aren't any stronger or weaker than the non-shiny ones. So your Sableye is fine the way he is.

[But...] I think he'd look kind of cool with sunglasses.