When referring to special skills, rage, is strong, often times uncontrollable anger, which can at times give great strength through adrenaline or other means to the person who has become enraged.
Rage, even though it can be considered a weakness, is also considered an essential skill for certain characters, whose powers are fueled by rage. Rage is an essential quality needed for Red Lanterns, for without it it, one couldn't use their power ring.
Other characters, like Hulk, are also fueled by rage. The madder he gets, the stronger he becomes.
Characters with rage