Nothing wrong with "Turn right 10 degrees". It just means that ATC wants you to turn right 10 degrees from whatever your current heading is. It is not important that ATC knows what your current heading was, they are just monitoring your track made good and just want you to make a small adjustment to it, probably to ensure separation from hills, other aircraft, better positioning for sequencing, handover to another controller etc. When ATC want you to fly a specific heading (vector) they will tell you.