"Mother Daughter Island"
Oh, you mean the Mother and Child Isles? Yeah, she looks similar to the Great Fairy Queen there, which probably indicates she's a powerful/important spirit. As for not being the MS, there are multiple similarities to it and her clothing, so for all the info we have now, the best guess we can make is she at least has
something to do with the MS.
As for what it will be called, I agree with Steven. It'll probably follow the "Person/Object+Verb" pattern most of them have, likely it'll be 'Sword/Spirit of something' or 'The something Sword/Spirit'.
...I'm still trying to work out the 'somethings' though. I'll edit in any verbs I think of later~
Of course it could just be something random and way out there that we'd never get