And the Duelist makes for all 5 classes. That was a difficult one. I had a nice +5 Blazing Assasins blade early on, but I didn't get Plate Armor until I bought it off the Imp on level 20. With the Duelist, blinking and slashing usually killed on the first hit. My second weapon was a plain whip, however, by selecting the proper skills, the +5 and Blazing effect from my blade gets applied to my whip. I took out 7 Wraiths with one attack using the whip.
The +3 Ring of Arcana I got off the Imp on level 17. Cursed of course, but that's why one always keeps a Remove Curse scroll handy.
The Ring of Might I found on level 4 in a random drop. It was +1. By using 2 of my Upgrade scrolls, I was able to use weapons and armor much sooner than normal.
I also had a Spell Book artifact that was basicly useless to me. When I found a Scroll of Transmutation I appied it to the book and got the Talisman... that was very usefull!