Very beautiful design. I like how you replaced her scarf-like-thing with really long hair, which is actually really abnormal for her since she normally has short hair. Fiora often does not get alot of love from players and riot, it would be could if they could do a little something for her. I put up a skin idea on the forums for a android/battle suit fiora, based off "Man of Steel"'s Faora, the badass secondary antagonist.
This is really amazing! You should really sell this to RIOT as a new skin concept for Fiora. She really needs a new awesome skin like this one. One thing though, she has a duel cloak usually attached to her right(or left I can't remember clearly) shoulder pauldron which I think could be added.
(slight critiques here) on a side note, you missed one of the most distinctive characteristics of Fiora. Her small strand of hair :3 although in this case you probably should make it a royal blue. Secondly, why does she have knives o.o she is a fencer after all and uses foils/longswords rather than knives. Otherwise, you did a GREAT job with the viewpoint, scenery, and outfit of hers. Dear god that sword. THAT.IS.AWESOME.
Lastly, she kinda looks like a mixture of Fiora, Katarina, Vayne, and Ahri (in an awesomely thought out, artistic, and futuristic way, of course)