@Eend made the deal on the condition that he would receive his items and he stated that multiple times.
Regarding bonding the account, you said when, not if. The reason you should be forced to bond them isn't against your will because you yourself said you would bond them, and the deal was made on that basis.
You will have to bond the accounts and give the items, or, if you don't want to bond the accounts you can just trade @Eend the value of the items on the account.
@Eend could you please provide the links to the gyazo's you posted in skype that proved the items on the account?
I truly don't believe you intended for this to happen and it's a weird situation so no TWC will be given at this time.