Okay, I'll tell about the name. Yes, you pronounce shay, like you say.
Right, banshee is written with two e's and pronounced ee. That would have to change too in order to be correct. Slip of the mind. (Anyway,yes,Branshea is meant to be the masked word banshee)
BranShea is two names put together. Bran from Brandon (not from all bran cereal etc.)and Shea.
Both characters come from a fantasybook I've read.I only love two fantasy writers: Tolkien (beautiful, comforting) and George R.R Martin (clever, witty and entertaining).Bran is an innocent boy of about 8 or 9 years old, crippled, a lord's son and a skinchanger. (direwolf)
Shea is a campfollower,a whore, beautiful, witty and clever. (until she becomes too clever and gets herself killed).
Why it had to be Banshee/BranShea is too long a story. But it fits in with the ensorcell-world.