So about that... is that how it is supposed to work or is it another homebrew? I googled berserker but I can't find anything in 5e rules. It seems like an incredibly powerful buff.
The full weapon attack as a bonus action perk of berserker *IS* a very, very powerful perk that berserker barbs get early. It's a strong part of why, in the rules, it's balanced out with a strong counter-measure - the increasing exhaustion levels.
