Bruiser fiora doesn't have the straight dps/ insane scalings of AD fiora that lets her deal the required true damage
For example, a
that builds
will lose 10/10 to a
that builds

or to a
with

And that's because, with fiora's build she only gets 7.5% max hp true damage per vital, requiring her to engage in extended trades with THE
, and once darius gets noxian might it's gg for fiora. Darius heals a LOT whenever he hits his axe
also can beat tank fiora because she deals max %hp damage, which scales with more hp that fiora builds. and poppy's damage while building tank is absurd on it's own. Plus, the above fiora build has very little lifesteal , so her trading won't be favorable to her
However, if
builds

you need to counter her with champions that have VERY high damage and can kill her before they get killed
Think on the levels of

Reason being, all of these champions can easily incorporate a
in their builds and smash fiora in before she gets off more than a vital if she dancing around waiting for her passive vitals
And if you just wanna beat her in lane, here are a few that can look to kill her and snowball

I'm mentioning Olaf, because I've watched streams of Smeb, Marin and even Faker play fiora into Olaf. Here's a hint: they STRUGGLED
Fiora for all her bravado has an "gimmick" dependent kit. Her riposte does nothing if the enemy doesn't have cc, her Q has an average base damage. And her bladework doesn't help if the enemy wants to be on your face. And her ult can be cleansed.
Protip: Pure damage fks her up. Not the damage of a bruiser, but the crazy damage from other Carries.
TLDR: Fight her with a Full damage carry if she's squishy, or with a juggernaut if she's going bruiser.
P.S Quite funnily, she has no steroids aside from her true damage passive, and you take that away she becomes crap tier compared to other carries