You expend some of your rage to strike your opponents with a more powerful weapon blow.
Benefit: While raging and using Power Attack, you can spend 3 additional rounds of your rage as a swift action to add your Constitution bonus on damage rolls for melee attacks or thrown weapon attacks you make on your turn. If you are using the weapon two-handed, instead add 1-1/2 times your Constitution bonus. This bonus damage is not multiplied on a critical hit.
Pathfinder Roleplaying Game Ultimate Combat. © 2011, Paizo Publishing, LLC; Authors: Jason Bulmahn, Tim Hitchcock, Colin McComb, Rob McCreary, Jason Nelson, Stephen Radney-MacFarland, Sean K Reynolds, Owen K.C. Stephens, and Russ Taylor.