Well today I hit my Dark magic on the ground by accident and it made a ding/scratch, but it didnt go through the metal or anything, but i was wondering if there is a way to like coat it so it looks like nothing is there (the ding/scratch doesnt affect play of the yoyo anyways) I asked my friend and he said to use wax and polish it, but i dont know 
in my personal preferance I use scotch brite pad and steel wool in the scatches and dings I had in my DM
First I use the scotch brite pad and scrub all over the dings/scratches (but I scrub all the parts of the metal rings) just to give it a rough scratch then I use steel wool to smoothen it out ( until desired smoothness ;D)
After that, just to add some bling, I just metal polished the rims
then
TADA…Looks like a brand new DM was born
hope it help
-KZ
P.S.
I am not reliable if something bad happens to your yo-yos its just how I do it, But I think it would not really affect much cuz I have tried it. But if you scrub very very very much hard we dont know (lol) But I think nothing bad will happen if you just scrub evenly around the metal rims ( I only tried this method for the metal rims my DM have )
Il try that thanks! 
you could also just try polishing it just to make it shiny
I just used the scotch brite pads just to remove all the nasty scratches ( I really mean nasty) in my DM and steel wool to smoothen it out
but if u got it correcty u might end up like this:
(got this picture from another forum from a polishing guide)
The one on the left is the polished one and the one on the right was not polished yet.