You can temporarily weaken an opponent with your unarmed strike.
Prerequisites: Wis 17, Improved Unarmed Strike, Stunning Fist, base attack bonus +2.
Benefit: Declare that you are using this feat before you make your attack roll (thus, a missed attack roll ruins the attempt). You can make an unarmed attack that deals no damage, but instead applies a –6 penalty to the target’s Strength score for 1 minute. Multiple weakening touches delivered on the same target are not cumulative. Each attempt to deliver a weakening touch counts as one of your Stunning Fist attacks for the day. Creatures with immunity to stun effects cannot be affected by this feat.
Special: A fighter may select Weakening Touch as one of his fighter bonus feats.
Source: Complete Warrior, page 106.