Winstonian
Grandmaster
Again, the structure of this would be defined to prevent some of these clear exploits. For example, it wouldn't work with knives, daggers, clubs, wands, etc. It wouldn't work in houses. Hell, you could even put a cap on the experience gained against one player during that span. Whatever the restrictions, it wouldn't be hard to develop a system that limits exploitation and vastly improves structured PvP.