This is my second build out of all that I have done. The build I have done on Fiora is focusing mainly on AD and Armor Pen. I like this build because it does massive damage and is good in 1v1 battles against most champions. This is a build that I like, but if you don't like it, then don't hate.

The armor pen. is for most of your attack damage to pay off and not be wasted by armor. Attack damage is, of course, for the damage. Armor is for being a bit like a tank, since it reduces some damage taken from physical damage dealers.

The masteries mainly focus on the 21/9/0. On the Offense side, there is Life Steal, Armor Pen., Attack Damage, more damage against towers. The kind of things you would get for an AD champion. On the defensive side, there is armor, more health, and health regen. All of those are necessary to stay longer in a battle, or too stay back.

The items are good, because it gives you attack speed, which Fiora really needs, and attack damage, also very necessary for Fiora because you can't build her with AP =P, the Bloodthirsters give a lot of life steal when added with the masteries. It adds up to about 40% life steal, which multiplied by the amount of attack damage you have is... about 160. This is good against a 1v1 battle because you can do massive amounts of damage, while healing at the same time. Infinity Edge gives a lot of attack damage, and a good amount of crit chance, which with the passive of Infinity Edge, does 2.5* more damage. Madred's Bloodrazor and the Black Cleaver are both for the attack speed and attack damage.

Exhaust is a good summoner spell for Fiora, because when you attack with your E spell and successfully land a Lunge or basic attack you gain movement speed. While the target is slowed you can attack many times to gain the maximum amount of speed you can gain. Then, while chasing you can use your Lunge and Riposte to easily catch up to your target, and if necessary, finish them off with your ultimate. If your ultimate doesn't finish them off, then you can basic attack and Lunge to get them low. Then, Ignite them for the kill.

Overall, this in my opinion is a really good build. Don't say this is a bad build until you try it. If this helped you with Fiora, then I'm glad I made this build. Have a nice day!