Reaver is completely unnecessary and gets in the way of items fiora really needs. Fiora's trading in lane is super mana efficient and I almost never run out of mana unless I've been straight out fighting to the death for whole minutes. Even spamming q off cooldown doesn't really dent your mana bar. You will only ever have mana issues if you literally qwe every single time theyre off cooldown, but even then q is so cheap that you can almost use it off cooldown to proc vitals just from ambient mana regen.
What fiora needs first is a tiamat and a vamp scepter so she can waveclear and sustain, maybe getting a spectre cowl or a warden mail early if in a super poke heavy lane that she just needs to survive early. Next she needs some tankiness, I personaly opt for a mid tier defence item of both mr and armor before I build more damage but other people can get away with just one until later. Phage is good on fiora as is BC in general but that doesn't become really useful or necessary until later in the game when people have a lot of armor.
I've found that fiora just is a lot more reliable as a half damage half defence fighter rather than a glass cannon adc type like your build aims at. You want to be making heavy use of your passive and ult in fights, not just trying to auto them to death like a master yi or something. Fiora is a different champion now then before, she's not an assassin who dives the enemy team.
All in all, your hypothetical build is expensive, has a poor item build path, wastes gold on mana regen she doesn't need at all, relies on black cleaver instead of laws whisper against tanks (so you have to stack it with several hits... and you have no tankniness to sit around for several hits), relies on autoattacking constantly to take advantage of all of your crit and attack speed, and will explode instantly in any teamfight unless you're so much more skilled than the enemy that you could build 5 ie's and it wouldn't matter.
For reference, the build I aim for is: 
. This build makes you tanky enough to fight long enough to proc your passive over and over and has great sustain from hydra+passive+ult heal+spirit visage, has 40% cdr to spam your spells super often and stick to enemies plus the phage move boost from black cleaver and the burst+slow field from iceborn makes it easier to chase and get into position for vitals. I also go 9/21 for masteries.
