These are all of the skills that Berserkers learn.

Block - Already learned
Melee Attack - Already learned
Rend - Already learned
Sprint - Level 3
Endurance - Level 5
Ravage - Level 5
Thrown Weapons - Level 8
Savage Strike - Level 10
Feral Rush - Level 10
Piercing Howl - Level 13
Recover Thrown Weapon - Level 15
Dual Wield - Level 15
Scent of the Pack - Level 18
Blood Curdle - Level 20
Death Breath - Level 20
Infect with Madness - Level 25