The gray wheel is a fine finishing wheel, it comes in various "grits", use a fine grit wheel and it will both debur the edge you wrote of and also polish it. Be careful to stay away from edges you want to keep as they are. Practice on a piece of barstock, offer the gunsmith compensation of course, and you may not be able to find one who will let you use his wheel. The wheels are expensive, and a new guy typically will wear grooves in the edge of the wheel. It's a natural (To the guy who pays for the wheels) practice to favor the area of the edge of the wheel that is higher, or if it is flat to play the part back and forth across the wheel edge. If you were here and asked this question I'd show you how to do this, but not everyone will.
I have a S&W PPK/S that made bloody tracks in the web of my right hand when I shot it, the gray wheel rounded out the sharp inner edges of the back rails of the slide so you would not know it wasn't made that way if you saw it. That helped with the shooting pains
