The idea of gaining exp for PvP has been proposed countless times and shot down as many times. It's a terrible idea. Gain your exp through PvE; it is also, like PvP, a vital aspect of the game.
Could you explain why its a terrible idea? Xp is lost when defeated by creatures similar to how its lost when defeated in pvp. What would be detrimental about it being gained in pvp?
Really Meahdros at your level you should know better.
Xp lost, and in your proposal gained by attacker, is for a large part of the game 4 or more
times greater than can be gained by PvE with the same amount of stam. So what you ask for is for PvP to be 4 times more efficient to gain levels than hunting PvE. Also have a look at the sacrifice buff, if a PvE hunter wants a tiny bit more xp it comes at a significant price in reduced gold income. PvP can as always pick their target for highest gold gain.
You're a big fella so i think you can take it if i summarize in one catching remark:
This is a classic example of someone wanting to have it both ways.
That said i do like the idea of revenge hit(s). To make it easier to code maybe make option on BB 'create bounty and accept it yourself' (bounty tickets used, no reward offered, double xp loss as normal bounty, max 2 lvl lost)
Oh and the BB is a failure because it's extremely easy to use as exploit