Playing the violin with your wrist and a blade is a term used by people who cut themselves that don't want to to know what they're on about. Usually its just called "Playing the Violin" but when used around other cutters they use the full term.
Person 1: "I heard that she played the violin last night."
Person 2: "Yeah, using her wrist and a blade! I hope she's alright.
Person 1: "Playing the Violin with Your Wrist and a Blade can be dangerous, but it helps her get through the tough times."