This drops off ANY of the first floor bipeds. I have investigated, and observed people acquiring them off Svartalf, Arachite AND (where I got mine, eventually) off those Duender. This rule actually applies to any item found on the first floor bipeds. Level to attain is NOT L38, as groups of L33's have got them. It is V.Rare IMO, having spent a lot of my L32-L41 in Spindelhalla, I only recently acquired my first. The look of it, is black (duh), with the wavy pattern and a black margin. Hoodless.
-Brannor McThife
[41st Level Troll Warrior. Euro-Prydwen-Midgard]