Weakening Touch

Improved Unarmed Strike (PH) , Stunning Fist (PH) , WIS 17, base attack bonus +2,

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.

A fighter may select Weakening Touch as one of his fighter bonus feats.

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.

A fighter may select Weakening Touch as one of his fighter bonus feats.

You can temporarily weaken an opponent with your unarmed strike.