% Max HP true damage is pretty stronk mate, but what really gets me is the tacked on heal.
Why does she need that? She already has a heal on her ult, plus most Fioras rush lifesteal then follow it up with CDR. It just makes trading with her impossible for most of the roster and very difficult to stop her if she gets even slightly fed. Even Jax and Trundle have windows of opportunity where you can either escape them or actually fight them. In comparison Fiora's feel few and far between if the player has a brain.
I think her cooldowns are too short, particularly her Q.