#28 - Jan. 31, 2017, 3 a.m.
What you're seeing through datamining regarding these items right now is EXTREMELY unfinished -- that's why we haven't enabled them for testing on the PTR yet, and currently don't plan to for at least a couple weeks. I wouldn't take their current state as anything more than "there will probably be some Legendary items obtainable through crafting."
They should make a lot more sense once they're in a more fleshed-out state. I'd love to be able to share more details now but, frankly, they're so early in the design process that most of the details don't yet exist.