An idea for Fiora's ult, which I feel doesn't fit

So I was thinking about Fiora's ult and a way to make it A: Fit her more and B: Seem more useful. While I've found a lot of use for the ulti, it just doesn't feel great to me. So here's what I thought up:

R: Grand Challenge Fiora gains a MS and AS boost (I don't know what the numbers would be) for maybe 15 seconds. While Grand Challenge is active, hitting a Vital will Refresh the cooldown on Lunge and cause Fiora to identify Vital on every champion within range of Duelist's Dance that does not already have one identified.

This would feel more like her old Ultimate, except she doesn't go untargetable and is fully controlled by the player. I feel like this would make a great use of her new passive and fit in really nicely with her new kit.