The user has gained insurmountable bravery and an almost inhuman set of abilities derived from rites of passage and special training received from generations of barbarians that came before. Barbarians live by a primitive code of conduct, which manifests itself as a natural will to fight for a cause or an instinct to both protect family and community to destroying the enemies that would threaten them. They, however, are not fighting for a greater-than-life ideal: To follow the path of a savage warrior is to neglect certain aspects of one's human nature, such as suppressing empathy and committing acts of extreme violence, such as pillaging the home of a defeated enemy, torture, humiliation, and assassinating individuals that have little to no involvement in the conflict at hand (women, children, elders).
Barbarians are archetypically portrayed as beings who can take heavy damage and use the heaviest weaponry available (although many "barbaric" cultures use little to no cloth in battle). Another staple is the presence of the berserker state, a mindless rage that overtakes the warrior during and after a ritual. This frenzy is the barbarian's greatest strength and greatest weakness, due to not only numbing their body to pain and dramaticly increasing strength, but also blinding their own sense of judgement. The savagery inherent to them is not a stereotype however. Instead, it is a mark of their philosophical way of thinking, the belief that one must embrace the deepest aspects of their nature be it for good or for evil, always handing their life to their primal instincts and being guided by them. "what doesn't kills you makes you stronger" is probably the best definition of their belief.