After all thoses messages, i can only see that the two parties are at fault there.
The two worst things for each side are definitely the "why ?" from Xol and the "i'm an admin" from Uthred.
To think this could have easily been resolved peacefully, but we got the two protagonists who just have a bit too much ego.
First : Xol, why the hell do you want Uthred to apologize ? Did he do something to you ? I'm quite ashamed that after his two posts you just didn't do a "Just relax man, i 'bought' it so that no people would abuse and get it. Tell me when you're online, and i'll trade it back. ;)", but instead a "why" that was just the best way to infuriate someone who had already lost his nerves.
Second : Uthred, in the beginning, it was your fault for messing up in the market. Just accept it, and with all your experience, of course you know you get things more easily when you're polite and understanding, than when you're raging. The way i see it, you're just using all this as an excuse to leave the game in a way everyone reminds you (most people already know you from crushing their skulls with a morningstart anyway, you didn't need this kind of publicity).
It's really a shame that all this happened. People are definitely not being honest this day.
A fair way to end this, Uthred should just put a proposition in the market, offering a longbow and 5k gold, for a MW langes messer. If we still see that offer after a week, it means Mr Xol definitely just wanted the item/ just wanted to make Uthred rage (offering a mw to a noob instead of giving it back...)/etc... If we don't, it means he's a comprehensive person, and still get a 5k benefit from it, for honesty.
One way or another, there's just one word who comes up for all this drama.... childish attitude never ftw.