hmm... yeah, that's odd. Actually, checking a few more, it looks like there's quite a few of the Aetherial items that don't specify their location. It's supposed to show it the way it shows that the Aetherial Elm Crook is dropped from Halatali, but I guess some of the items, like this one, don't include that part.

I can tell you that all Aetherial items are dungeon drops. With a required level of 35, I'm guessing that one's probably from the Sunken Temple of Qarn, but I don't see anywhere that actually says so. (XIVDB doesn't have a location for it either.)