Well Master isn't apparently dead and will be returning eventually. He was supposed to come back in Omega Flight.
Depends really how Mandrain uses his rings.
Martial arts wise, Master has KO'ed Namor with a single nerve strike, and broke Sasquatch arm with one move. He also matched Iron Fist in one of his clone bodies that had his mind (Master's mind). Ideally I would say Mandarin is potentially more skilled MA, but it's not a blow out by any stretch.