[Futaba-chan]

Spoiler:

Originally Posted by Simon

Is Grand Shrine Empress a translation of オナシア Onashia?

No, Erii addresses her with a specific title that translates to that in addition to her proper name. I'm at work now; I'll post the exact line when I get home.

Spoiler:

an AODer noted that the under-17s wear necklaces with two wings, but adult males have only a right wing on theirs: compare Erii and Erif. Does this mean adult women wear left-winged necklaces?

The necklaces appear to be radially symmetrical; how would you wind up with a "right" and a "left" to them? In practice, they'd tend to wind around with the wearer's movements.

It suggests that at least in a spiritual sense, people really are androgynous before they go the spring.

That's a very nice insight, although it works equally well without assigning specific necklace sides. Of course, anime does tend to go for impossibly cool clothes, so there could be a right-versus-left symbolism for necklaces that magically never twist, but my guess is that one wing means a military member who isn't a Sibylla, and two wings means one who is.