League of Legends (LoL) Question: Why Get Berserker Greaves on Fiora

I can't simply see sufficient reasoning behind it.

Ninja Tabi and Mercury's Treads I can see the use for as she is melee. Ionians due to extremely long cooldowns on her ability and will increase her damage output because of it.

Berserkers on the other hand only give 25% attack speed (besides the speed boost) and no other perks besides being cheap. It makes sense on other melee carries like yi and tryn because they scale with attack speed and crit, and of course on ranged carries because they need to be able to pump out as much damage as possible. But fiora scales with damage, both with her abilities and auto attacks.