Finally dropped today off a battle-scarred bazu at -998, +1696, 312. Up on one of the cliff walls of the valley in the south. Started to get the inkling that it is more common off the bazu's based on the other posts. Did done the named and no luck, killed easily 300+ murks and nothing though. Hope this helps someone.
My Wife and I worked on my guantlets for almost a month. 4-8 hours a day, every day. That drop sucks... There's no reason why the thing should be so rare. They just did it to road-block it seems.
I pulled every murkglider in the zone with my sk. usualy about 10 at a time due to distance agro dropping. I had to clear the entire zone 7 times to get one to drop. It did drop by Wyrmsong on the 7th clear.
I had this drop twice for me while soloing. Bad news for bards though, they were both off a bazu in Nobles Causeway, so it'd be a bugger to try to farm those for epic, since they only spawn one at a time. I got 2 in probably 20 hours worth of soloing in that spot total.