Righteous Wrath

 
Prerequisite(s): Rage class ability
 
Benefit: The first damage that you deal to an evil opponent while in a rage, causes that creature to make a Will save vs DC = 10 + Raging Class Level + Cha bonus, or be shaken until you withdraw or are incapacitiated. You are able to keep a clear mind while in your rage, so you suffer none of the penalties tied to raging other than the exhaustion afterwards.
 
Source: Book of Exalted Deeds