Do you have a picture? Are the scratches on the smooth or textured part of the grip? It'll be fairly easy to clean up the smooth part, with some very fine grit abrasive, followed by a buff. But G10 dust is extremely dangerous, you don't want to inhale that stuff... If it's scratched through the textured area, I'm not sure there is a fix for that.
G10 is pretty hard, much harder than wood, although I'm not certain how it compares in hardness to carbon fiber. Maybe other will be along to answer that. Good luck