The material below is Open Game Content from a 3PP Source
Deadly Stroke (Combat)
With a well-placed strike, you can bring a swift and painful end to most foes.
Prerequisites: Dazzling Display, Greater Weapon Focus, Shatter Defenses, Weapon Focus, proficiency with the selected weapon, base attack bonus +11.
Benefit: As a standard action, make a single attack with the weapon for which you have Greater Weapon Focus against a stunned or flat-footed opponent. If you hit, you deal double the normal damage and the target takes 1 point of Constitution bleed (see Conditions). The additional damage and bleed is not multiplied on a critical hit.