I’m not (nor do I believe is anyone else) casting aspersions. I was simply explaining what might have happened. Whilst I agree that the OP does deserve his property back. Upon refunding, Ebay may have told the buyer to destroy the item as the selling of knowingly fake goods is a crime.
In a strange twist of fate, I have been in a similar situation to the buyer, in which I unwittingly bought a fake (im not saying yours is fake OP) Sling on eBay. The manufacturer confirmed it was fake, the seller refused to take it back. eBay refunded me and told me to destroy the item.
IF the buyer has managed to prove that it is indeed fake, then following the logic of – the item was for sale as the seller had no use for it/wanted money, but the item is fake and cannot legally be resold at all, therefore the item has no value.