They are a rare drop from Ulthirians (and I believe from other humaniod mobs like thugs, ruffians, Gadai). You can also ask in ooc for someone to trade/sell you one.
I believe that's also a rare drop, but I've never gotten one so I could be wrong, or else I've just never fought a number of the mobs that drop it. Asking in /ooc is the fastest way to find out this stuff usually.
