Fiora is broken, not overpowered - broken.
Hear me out, I believe that Fiora is NOT overpowered, but instead has too much power in one area, and is weaker in another. What do I mean by this? Her ultimate, is a Janna ultimate, plus three Garen ultimates combined, into one. This is NOT how a duelist is supposed to be. Her ultimate is literally, Grand Challenge, for a reason. It's a challenge, not for healing.
A fiora once told me, when I was playing Nasus, "Fiora is an anti-tankburster!". Which, in my opinion, should NOT be the case. Logically, Fiora should be a very snowball type champion, and when behind, should NOT be able to fight. Sort of like Riven, because, a duelist who is weaker, can not fight someone who is stronger. Dealing true damage is ridiculous, and needs to be changed into something else like reducing CDs of other abilities, granting more movement speed, and dealing a bit more damage.
When you deal 1500 damage to someone, that is literally, 3 Garen ultimates, on you, that is true, and gets a Janna Monsoon, twice as powerful. I'm not kidding. Fiora players can easily reach the top leaderboards for healing, which I find ridiculous. Fiora should be more offensive, and dangerous, and not a safe choice if you are looking to hit the vitals of an opponent, and expect true damage of 100 to come out.
Fiora's passive needs to be changed from true damage, that seems that Riot has seemingly slammed on to Fiora because they didn't know what to do, and gave her healing, because it seemed "right", even though it definitely wasn't. Giving healing is not the true identity of Fiora, and should instead give a speed boost to herself, and will reset all cooldowns on her abilities, and give massively increased attackspeed.
I've seen enemies from 100 HP, turn to 1000 HP, in an instant, just because of Fiora's ultimate. This is overpowered, and power needs to be shifted around. Nerfing her ultimate allows Fiora to get a stronger W (lower CD), and a stronger E (more slow, more dmg), and making her reset cooldowns will allow her to be a true duelist to fit her identity.
Riot slaps on true damage, because it "fits" her kit, when in reality, it's an unhealthy mechanic, being impossibly difficult to build against, and play against. It's unfun, and should be removed, and changed. There is no doubt that Fiora's ultimate is OP, but, to the diehard Fiora mains who will probably downvote this post, go ahead. I am prepared. I believe that power should be shifted, and Fiora's kit should actually cover her identity like it truly should.