Again, this is all about perspective.

Joe Doe Warrior gets two rounded, and yes, it sucks. How can it be that luck can win the battle? How can it be that I prepped and used strategy and some stupid random number generator just dealt 400 points of damage to kill me when I was in the lead? How!? Why!? KHAAAANN!!

If you look at it from the berserker's perspective, he's probably got about a 40% pk ratio, and more often than not, deathblow doesn't fire exactly when he needs it to. In fact, with my luck, it typically gets parried or dodged, and my regular hits are the ones that land.

It's actually a relief to finally have that one battle go your way, where you can land a bash and get a pair of deathblows before the lag wears off. But in my experience, that's far beyond the norm.

The norm is, it doesn't go the berserker's way.

Which brings us back to perspective. If you fight the berserker and it happens to go his way, it's going to go really really badly for you. That fight will stick out in your mind, and you'll think the berserker is overpowered. You won't really think about the other 4 fights you had with him this week where you sent him packing (or regearing).