It works.
If it's triggered by a player hitting a player, then it's absolutely useless.
Why?
Cause, AFAIK, the dmg you take is reduced once, for pvp penalty, and the dmg reflected is reduced AGAIN...thus, it does 1/12 of the dmg it should.
If it's triggered by a player hitting a minion, than it's brutally deadly, as there are no dmg return penalties and minions take aditional dmg from players, and you'll often see melee chars doing 1-hit-suicides.