>>96109020
I know that GURPS Martial Arts has things like:
>Counterattack: technique for any melee skill. It gives your foe a penalty to defend against your next attack after you successfully defend against one of his own attacks
>Feint: action option that lets you roll a Quick Contest of weapon skill against your foe. If you win, then you penalize your foe's next defense by an amount equal to your margin of victory. There are also rules for Ruses which contest IQ-based skills, Beats which contest ST-based skills, perks that let you contest noncombat skills like Acrobatics or Sex Appeal, and Defensive Feints which penalize attacks instead.
>Stop Hit: action option for Attack/Wait. You declare that you intend to strike into your foe's attack, attacking him at the same time he attacks you. Both of you make your attack rolls at the same time. Whoever scores the higher margin of success on his attack roll gives the loser a penalty on his subsequent active defense roll.
>Stop Thrust: action option for Attack/Wait. If you attack a foe at the same time that he is charging you, then you might get a damage bonus depending on his current momentum.
>Riposte: defense option for Parry. Lets you take a penalty to your defense roll, and on a success, give your foe a penalty to his own defense roll against your next attack.
There are also action options like Evaluate, All-Out Attack, All-Out Defense, and so on.
If your foe gets desperate or overconfident and overcommits to an All-Out Attack trying to take you out in a single decisive gambit, and you survive his assault, then he'll be defenseless against your next attack.
Meanwhile, taking an All-Out Defense can help set up a Counterattack or Riposte by giving a bonus to defend.
For longer duels, taking an Evaluate over multiple turns can give a small cumulative bonus to both attack and defense that'll be useful for setting up any fancy trick you might have in mind.