Help dating this robe

I don't know the fabric. It's heavy, soft, with a bit of a shine and rustles when moved, like a satin. There's a lot to it. I laid it over my latest project to try and show how much fabric is involved. No tags anywhere. Thanks for your help!

 

I measured the hem around and it's one inch shy of 12 feet.

 

Adult baptismal robe? Peignoir?

 

I also thought it looks like a church robe, made for a special holiday choir, special blessing of some kind, or similar. Or a costume?

 

I have no idea but I wondered that too, if it wasn't some church choir costume or something.

 

Actually, I think it may be for adult baptism. This is worn for modesty before entering the pool.

 

Thank you! I think it will make a fantastic adult Christmas angel costume. lol