City faction in Faydwer

[Messianic]

Your best bet is Kelethin - I had a DE wiz on live who I made non-KOS. And it's not all of Neriak - I'm pretty sure it's just the warrior guild (Indigo Brotherhood). Plenty of Dark Elves, Ogres, Trolls have become non-kos with Kelethin without affecting their Neriak dealings at all.

One note - the banker is on Kelethin Merchant faction, which is not raised by killing CB orcs. You have to do a LOT of additional legwork to get that one up, and you'll likely start out glare/scowl with the banker (i.e. he attacks you and takes a bunch of guards with him).

But luckily for you, you're a monk with sneak, so that extra effort isn't worth it. Sneak behind banker, bank quickly, profit.