now i can't explain this 100% so you might need to test it out... but this is what happened.
I was in the arena and some warrior jumped in... i think he must have heroic leaped inside or something, either that or he found a spot to wall jump in there. Either way he got in.
By him getting in, he helped me kill the guy i was on (wasn't hard, still only rank 1... but he was in there with me).
The amazing thing was that by him helping me it counted to his kill. He was rank 6, so he got a free win out of it.
If someone can replicate this, that would be amazing... true amazing glitch.