For items like this your almost wasting your time if you dont take a thief with you, fine you can get lucky and get the drop without one, but considering he only spawns once every three hours or so, and its unfair to ask a group to stick around for that time or come back, so you may aswell maximise your chances.

Also i dont like to spread ff rumours much more, but its also better to let the thief get the last hit, i never used to believe it made a difference but i often camp things like this with a thief friend of mine who swears by it and there have been a number of events which have made me think there is some truth behind it. Anyway for a one off fight, it cant hurt your chances lol.