I did a search for the item and couldn't find a post on it so I decided to start this one. I've seen [The Gunblade] a few times and there is no disenchant info for that item.
Also, I did the Brewfest boss once and nobody wanted an epic trinket that dropped. Enchantrix told me it would disenchant into a crystal but I got a message saying that the item was not disenchantable.
That item was non-disenchantable last time I checked. And we constantly have to update our non-disenchantable database when new items are added (like the brewfest trinkets). The good news is that your local copy updated automatically -- when you see new non-disenchantable items, enchantrix remembers them.