Knockout Training (Ex)Source Blood of the Beast pg. 29
The fighter takes no penalties on attack rolls when attempting to deal nonlethal damage with a weapon from the associated fighter weapon group that normally deals lethal damage. In addition, whenever the fighter deals nonlethal damage with a weapon from the associated fighter weapon group, he doubles his weapon training bonus on the damage roll. This doesn’t stack with other advanced weapon training options that allow the fighter to double his weapon training bonus on damage rolls, such as trained finesse or trained throw.