So every berserker I see is running around, smacking enemies into the walls and then finishing them off. I created one berserker and I have lvl 5 now. I don´t know why,but my power attack won´t move with my enemies. Only cobblestone on rope and crushing blow works. What´s the problem? Should I learn finishing blow so I knock them out or what?

What you need is at least a lvl 4 weapon. The knockback doesn't work with lvl 1 weapon. Craft it or buy it and then you will dominate the fight arena

Thanks, I had no way knowing!

And if you couple that with finishing blow, you will lay down some serious kills, even on other orcs. A knock-down and finisher gets them every time.