Recently playing through a game as a melee character and had the misfortune to stumble upon a threatening room of ghost kings. My character was a drakeling, which mean that this was literally a death room, as soon as i stumbled upon i I had to hit a wand and GTFO out of there.

made me think, mobs like ghost kings / lords are literally, one-two hits and you are stone cold dead with anything other than a elf. However the experience for killing such a dangerous foe is actually very low.

My suggestion is the experience should be according to the risk: high for a troll, low for an elf. A ghost king is actually, far, far more dangerous than even a greater moloch, so the experience should be around the same level.