So, I just looked at the 3 versions of Gananana. Felt I'd give my opnions. Sorry if I cause any offense, it's ALL awesome artwork and I love it and that you did it.
Thief: Perfect. It looks epic, in fact, almost too epic to be a Apprentice, but that's never a bad thing. The main issue is it makes the other higher ranks look worse in comparison, and that's always a good issue to have. Perfect in every way.
King: My main issue here is that Thieif looks better then it. No real complants with the artwork itself, it just looks as though thief would be the higher rank if that makes sense. Also, it does not have the mark of the quadforce on it's hand, but that's just nitpicking. I guess if I have any ideas it could use more regal and evil at the same time. Not like spikes or anything, but a sort of subtle evil regalness. Also, the shadowblade should have transformed from a dagger like object into more of a bradsword, fitting the regal theme. Think a dark version of Gannondorf's Sword from Twilight Princess.
Gananana: My main complaint here is it's to simple for a Master. It's mostly my own fault, but I was hoping you'd use the Ganana pic as a VERY rough basis for it, and would throw in some of Ganon's pig form and some other stuff since it's a reference. Basically, it could use more: more eyes, more tentacles, more mouths, more arms, more Ganon Final Form form in it ETC. My only advice is this: How would you expect Gananana to look if it were Ganon's form in a Zelda Game?
Having said that, the artwork for all of them is VERY good and I love the fact that you drew them for me. You did a great job and I sincerely appreciate it.