Major Berserk is often confuzed with major brutality. Major Brutality is a buff that increases weapon damage by 20% , this buff is obtained through certain skills such as weapon skills and class skills, or armor sets.
Weapon skills: Two handed skill= Momentum (lasts 33sec) / Dual wield skill= hidden blade (lasts 20sec). Class skills: Dragonkights have Igneous Weapons skill from under thier earthen heart section (Igneous Weapons is a morph from molten weapons) (lasts 30 seconds, give to allies aswell) / Nightblades have Drain Power skill from thier siphoning abilities (lasts 20sec). All skills mentioned give Major Brutality buff.
Damage hint: If someone was a Nightblade, Two handed, Dual weilder; they can stack the buff together to reach over %60 dammage bonus. Some nightblade abilities give *minor brutality aswell.