For touching up your matt-blasted finish, I would use fine (200-400 grit) emery cloth and gently tap it using a small hammer. The grit particles duplicate the original blasting effects, and a couple of minutes of this over the scuff marks and scratches will restore it's appearance.
Keep in mind that all blasting rounds off fine edges and markings, so stay away from details you want to keep.
This also works on guns that have smooth shiney spots from wear and rubbing against holsters, etc.
John