From the introduction:
Not all barbaric warriors are hulking slumbering savage brutes; some are quick agile savage brutes. The path of the Furious Dervish is for those quick warriors that prefer to become a flurry of attacks and rage despite their size, much like a cornered animal.
...
Some warriors prefer to fight up close an personal. While most adventurers engage in fist fighting from time to time and have heard of exotic warriors from distant monasteries few dare to oppose those who take glee at snapping necks. The Mauler's path is dirty and bloody, and they wouldn't have it any other way.
...
Some barbarian warriors are more than just fighters, combining their martial prowess with a shamanistic tradition. This mystic understands the ways of the spirits and acts as a bridge between them and his warrior brothers.