Resounding Blow( Book of Exalted Deeds, p. 45)
[Fighter Bonus Feat, General]
Your mightiest attacks cause your foes to tremble before you.
Quell the Profane (BE) ,
Whenever you deal a critical hit using a melee weapon with which you are proficient, your opponent must succeed on a Will save (DC 10 + 1/2 your character level + your Cha modifier) or cower for 1 round. A monk's unarmed strike is considered a melee weapon for purposes of this feat.
A fighter may select Resounding Blow as one of her fighter bonus feats.