Orc warband,
Maybe create a feat for non-barbarian types.
Blood Rage
Orc's are bloodthirsty by nature. Some Orc's develop an ability to rage when exposed to significant amounts of blood. As an Orc goes up in level more blood is needed to create the rage effect. For every 2 points of damage dealt that draws blood an Orc must make a will save or go into blood rage. A successful save negates the effect however a failed save makes the Orc fly into a blood thirsty rage. This results in a +2 to hit and +2 to damage he also gains a +2 to all will saves. For every level achieved 2 more points of damage must be done before making the save. Example level one 2 hp level two 4 hp level 3 6 hp, etc.
This feat can only be taken at first level. However if an Orc rages more than once a day for every three levels he must make a fortitude save or lose 1d4 hit points from body fatigue. Also he will suffer a cumulative -1 to fortitude and reflex saves.
Note A barbarian Orc can take this feat but can rage the normal amount of times for a barbarian without taking the noted penalties. Also a barbarian receives the raging bonus afforded his class. However if he rages more than alloted for his class he suffers the same penalties.