As someone who loves Fiora's old ult, can I give a suggestion?
I understand it has little counter play, so it makes sense to change. But I LOVE the animation of that ult. Nothing screams badass like disappearing and reappearing like a ninja.
So why not just combine the new and old ult. Take away the max% damage and heal, and instead, if Fiora strikes 3 or 4 of the vitals, she activates her old ult.
Now her old ult has counter play, and those that love her shinigami moves can rejoice that it's not gone completely.