Nostalrius Begins - Quality wow vanilla realm (1.12)

Not sure where else to take this, really, but a very "friendly" warrior ninja looted a blue BoE from our entire group. We were (5 of us) questing in Alterac Mountains when a blue BoE axe dropped. Immediately I collaborated with the group to ask if I could Need, granted I was going to use the item as it was very good. Nobody had an issue with this, so I needed.

The warrior chimes in.
"That's going to be my new tanking axe."

Okay, whatever, he's rolling against me, that's fair. He's literally using an axe right now, anyway. His current axe was a blue BoE, and 5 DPS higher than mine, so I was a little salty, I admit, when he won the roll. This dude was fine. He was nice to everybody. Until we wiped directly after he wins the loot.

He left the group without another word. 10 minutes later, my beautiful beautiful axe is on the Auction House. I'm really upset by this. It had 11 more DPS than my current weapon, and instead of rolling fairly, he decided to lie to 4 people to make some in-game cash.

It's pathetic, and I really want to know what I can do about this (besides publicly shaming him. I'm going to do that so long as it won't get me ban. People need to know.)

I don't think the staff will (nor should) do anything about this.

These types of issues are typically a matter of community self-policing. In fact, I think there are some threads going on about known griefers/ninjas as a means of keeping the community informed as to who should be avoided when forming groups.