M.S.
Poor baby...I would try 2 things...transfer his pinching/scratching technique to an object like an stuffed animal or blanket. While he is awake show him how to do it so maybe he will be familiar with it at nighttime/naptime. Second, at 8 months if you want to rock to bond, read books, cuddle, feed thats great but I would suggest you let him start putting himself to sleep. Find a bedtime routine that works for you and then let him and his "pinching" friend fall asleep together in his crib with out you. Good luck and like everything else don't expect change quickly. He will have to change habits and relearn his comfort method...and you can heal ;)