I found 'a seedy-looking human in a bad suit and hat' and found out
he offers a quest (sort of). He gives you jewels for bringing him
a list of items he asks for, which you can take to the drow summoner
a little west of arelium. You have to get a corpse the summoner requests and
then protect him while he does a ceremony. Then you can get a piece
of armour from a merchant and get it enchanted by the drow. Having a spider
around for the ceremony helps, according to the drow. Beanos made me an
o-yoroi (for free, thanks!) and Endure helped with the enchantment process
and helped me figure out where to go once I had the jewel.

Cool quest!