Ugh, I HATE berserker's greaves.
It's that item that you just HAVE to build as an AS reliant champion or else everyone goes insane. It honestly should be removed as it gives a stat that not only is purely damage based thus making it the best choice, it's also way too common, unlike MPen.
It's probably the worst item in the game, it gives DPS on a role that's already pressured to give up build diversity for damage (ADCs) while not giving anything unique (Unlike MPen boots, jungler items, or support items).
Honestly, the game would just be so much better as I can't see a champ that can easily use such a tiny powerspike but at the same time it's the only upgrade allowed if extra MS is needed from it.