So, if I recall correctly, the designer of this deck has noted elsewhere that the idea behind the name is not so much about mysticism, as about secrets and things "hidden from view." (This is the third definition in the Webster's I have.) So, the deck designer pluralized the name, as would do if he were to name the deck, "Secrets."
I take this to mean that the deck has some hidden features.
I like the way the deck is shaping up; the designer has responded to comments on the project and has made some tweaks to the cards. He's made the indices narrower, and expanded the size of the courts. It's looking pretty sharp, imho.