He made his transaction via paypal and asked me to check the balance. There was the amount we had decided on the weapon and I was thinking 'my barb is going to be OP with this'. After I expressed my appreciation to the guy and gave him the weapon, I received an email that said 'An unauthorised account activity ...' from paypal. Apparently the guy filed a claim on this transaction that it was unauthorised. Shockingly checked my balance the money was gone and paypal put a 'hold' on that transaction. They required me to file evidence on that shipment is sent or delivered. Since the trade was done in the game and I didn't record or made any screen shot, I don't have proofs to it.
I believe you all know how it feels when you find a legendary item in the game and more surprised to see the roll. This was one of the best items so far I found in the game and it feels soooooo sad to loose scams like this.