Hmmm, though i just replied to this. If I did and their is awful lag then I am sorry about the repeat.
The only cape quest that I am aware of is actually given just inside the entrance of Crushbone. I couldn't use it and I think I ended up sacraficing it to my God. I am not certain that this is the cape you are referring to because it is a lvl 26 cape. If someone has knowledge of another then please share it.
http://eq2i.com/articles/Dishonored_Dead
Zoo