I just went to the Kings champer in Dire Maul. Before you kill the King there are some ghosts along the wall. You can't kill them and they cant hit you. I just bought along a lot of white (no BoP weapons) and had all my toons attacking one. Whenever they maxed their skill they just traded weapons. Even my mage has maxed all her weapon skills that way.

I dont know if Blizzard stopped this but its easy and can be done afk. The main thing is DONT kill the king. Just enter the chamber and head along the wall