Got one of these because I was bored killing a Weapon while waiting for somebody in my party to tele. Didn't know what its for at 1st, but it doesn't seem to be worth the effort unless you are just trying to complete as many quests as possible in Windurst.
I got it off a mob in Xcarbard. I believe it was off one of those "ghost" type monsters (dancing weapon look-a-like). Either that or that "Eye" monster. I was on my way to finish off the Chaos Elemental for the BLM af1 quest with Tyrrlis and Nicot the paladins of Seraph. We got the drop rather quickly by accident. So i dont think its a hard drop.