Probably the easiest way for a low skilled character to get high end items is the Minotaur Strong Box quest.
The quest involves killing red healers (best found in Ilshenar close to the sacrifice shrine), gaman and then running to the back of the Labyrinth in order to collect minotaur artifacts. At 80 skill, you could probably handle the healers and certainly handle the gaman, but the artifacts will be tricky. In order to get them, you'll need invisibility potions and a bit of luck. The invisibility potions are for whenever anything attacks you (you'll likely do ok once you get past pyre if your healing is good) and the luck is in not letting anything hit you. There are a number of monsters down there that WILL kill you easily (Miasma, Rend, Pyre, Grim, Mistral), so avoiding them is the key.
The best thing to do is load up on as many artifacts as you can carry so you don't have to go back as often for repeating the quest. Then you can load up on maps from the healers, gaman's horns and just finish the quest over and over.
It will be very difficult for a mid level character at the end, but it's still the easiest way to get high level items apart from piggy backing on a peerless run (we take new people to Mel all the time) and waiting for the corpse to turn public after the fight.
And if you don't want to do that, then demons seem to give me the best items from the mid level content. I've even found a few items from demons that I wouldn't expect on anything but the highest end monsters.