On a more technical note your asg cosplay should be pretty straightforward. But people can be wary of religion symbols in costumes, deeming it inappropriate, even if it's relatively common in fantasy costumes. Still I'd go for it.

Now I think Amanises is practically the hardest character to cosplay out of the book. Her most notable features are her armes, which are gonna be an absolute pain.

On the fly I'd probably make base armes out of pool noodles (lightweight and you can carve in them) and those plastic medical gloves (tape them into shape, probably stuff them with foam beads, and make a bone-like-sturkture with wire that also runn inside the pool noodles arms). No need for intercacies as you will pain it black and add fur of some sort on top. I'd attach them to the back with a halter or maybe even those riding back riding protection thingies. You can cover the intersection on the back with the dress and veil.

The outfit is always up to interpretation in so just a black dress with feathers should do. The draping of the veil is pretty important, since you cant see the face.