I thought the green beam was part of her dress, an open gore as it were or the pinnicle of a support like a pyramid. this is very much a Goddess person, showing that she has the power. Like a traditional version where the HP holds a scroll, she holds a crystal ball that she can see the answers in by scrying. It is rather....staid? unmovable? stable? but the High Priestess IS stable, she waits for the people to come to HER. So this, thinking about it, is rather traditional!
THE HP as I have said elsewhere, is the librarian of the deck, not because she is female, but because she is the holder of the information. Ask her the right questions, and she will give it to you straight.