Quote Originally Posted by Xiomara View Post
I don't think the servers would be involved, it'd be more a client side thing. The server confirms the kill, but the client is responsible for determining the job and applying XP, before reporting said XP increase to the server.
You'd still need a way to sync data between the client and server, what you're proposing is not a simple solution.
the game would have to keep a buffer of kills made, and the server would have to connect the kills to the client list of kills, that could cause problems if the lists were ever out of sync, if lag happens, or packets go missing, then future kills would have bizarre effects.

It wouldn't be too much of a good idea to do such things client side, there are reasons why such things are handled server-side in almost all MMOs. The more mission critical things you do client-side the more you open up your game to be exploited.