the only way for there to be a fair reward system for pking would be through mini-games, open world pvp is far too easy to abuse
the game doesn't need more sources of ec coming into the economy, it needs more ways for them to be drained out. make an arena that cost x-amount of ec to enter, person with most kills at end gets (all ec-20%), easy. the system and tools required to make something like this are all public, agatio could do it without breaking a sweat