Does the target of a successful feint lose his active defense?
No. A successful feint does something to lower or draw the defender’s guard, but the defender does not necessarily execute an active defense in response. Not all feints are fakes (and not all fakes are Feint; see Deceptive Attacks, p. B369). One can fake an attack, but one can also use rhythm (“left-right, left-right, left-left”), stance (a kick after shifting one’s weight as if to punch), deception (look left, strike right) and aggression (beat the foe’s weapon aside) to reduce a foe’s chance of defending. GURPS abstracts all of the above into a “feint roll,” so it would not be altogether realistic to have a feint “use up” a defense. But now the target’s player knows the feint worked, and can react to it. In reality, the target of a feint isn’t going to know he’s been feinted; if he did, he wouldn’t have fallen for it. However, the player will know he’s lost the contest, and may decide (for example) to run away. The best way to play feints is for the GM to roll all combat rolls for NP
No. A successful feint does something to lower or draw the defender’s guard, but the defender does not necessarily execute an active defense in response. Not all feints are fakes. One can fake an attack, but one can also use rhythm (“left-right, left-right, left-left”), stance (a kick after shifting one’s weight as if to punch), deception (look left, strike right) and aggression (beat the foe’s weapon aside) to reduce a foe’s chance of defending. GURPS abstracts all of the above into a “feint roll,” so it would not be altogether realistic to have a feint “use up” a defense.