Warriors have one role and one role only. That is to tank. Warriors are the absolute top of the line when it comes to taking damage from powerful enemies. Warriors are often sought after, especially in raids, to tank, due to their massive health, stamina and defense. Warriors sometimes pull enemies to groups, but this is only if one of the more adept pulling classes, such as Monk or Ranger are not available.
Warriors are only able to solo at low levels, and soloing should not even be attempted past level 35. This is due to the fact that they have absolutely no magic abilities and therefore no abilities to heal, past Bind Wound, which heals a minimal amount of damage. Every battle encountered will dwindle health and increase the time it takes to restore the massive health pool that is both blessing and curse to Warriors.