After approximately 570 hours I finally got it. The grand mastery charm after getting 1000 kills on every single gun, riot shield, rpgs, knife : r/ModernWarfareII
Papa John's (UK exclusive) weapon charm "GHOSTED" : r/ModernWarfareII
How to Inspect Weapons in Call of Duty Modern Warfare 2?
HOW TO UNLOCK ALL FREE WEAPON CHARM AND OPERATOR SKIN REWARDS IN MW2! (MW2 Free Rewards) - YouTube