The problem with PvP leveling is that it is either going to be easily abused or very crappy way to level.
One cool thing I saw in Redmoon Online was that there was arenas set up throughout the game with level caps, so that way you won't have a level 99 power-gamer dominating all the weak level 10 dudes. Though, it was nothing more than an arena. It would be nice to find some way to incorporate EXP into an arena battle without having it easily abused. Just giving people exp per kill can easily result in a high level vulnerable character (ie mage) to be beating senseless by a lower level. Lowering EXP on death doesn't really bring any new EXP into the system, either.
Maybe organized small (around 4 people) battles that happen only every X minutes where the winner gains EXP. But along with that, every time you win, you progress to the next "stage", and if you are the first to die, you go down one - everyone else stays on the same level. You only gain exp if you win, you don't lose any. This keeps people on the fighting of those near equal to them resulting in some good and close battles, along with prevents you from cheating the system for EXP as easily.
The problems I see with this, though, are:
- People can make sure they die first so they can win their next fight easily. This could probably be fixed by making 2 winners (last one left gets more exp than the other winner) and 2 losers, making it pointless to TRY and lose. In fact, that sounds a hell of a lot better...
- You are going to need a LOT of players (at least over 50, though over a few hundred would be better)
- People who just join after doing a lot of PvE or enemy fights are going to be in the wrong ranking. You may have to write a check for if they level a few times outside of the arena to automatically place them in what you believe is right for them just so they're not so far off.
Hell, I'm liking this idea now, I think I might actually try and use it. MINE!