The new edition of Exalted has a variant of this mechanic. Or, well, two variants.
One is straight-up magic points. When you're in combat, you get 5 "motes" of Essence each round, whereas you normally recover them at a similar hourly rate. But that's just a convenience so the Exalted can power their cool tricks in battle.
The other is Initiative. Most attacks are Withering attacks, which "steal" initiative from your opponent. You're still trying to kill them, but mechanically the effect is that you maneuver them into a worse position where they're unable to defend themselves properly - at least until they steal the initiative back from you. But when you feel you have a big enough advantage in Initiative, you can instead make a Decisive attack that inflicts real damage, and resets your initiative (assuming it's still relevant). The damage of a Decisive attack depends solely on initiative - armor, weapons, and all that stuff matter for withering attacks, but not for decisive ones (which is a little weird, but there it is). Alternately, there are a number of Gambits you can perform instead of a Decisive attack - if you want to push someone around, or grapple them, or disarm them, that requires a Gambit.
One is straight-up magic points. When you're in combat, you get 5 "motes" of Essence each round, whereas you normally recover them at a similar hourly rate. But that's just a convenience so the Exalted can power their cool tricks in battle.
The other is Initiative. Most attacks are Withering attacks, which "steal" initiative from your opponent. You're still trying to kill them, but mechanically the effect is that you maneuver them into a worse position where they're unable to defend themselves properly - at least until they steal the initiative back from you. But when you feel you have a big enough advantage in Initiative, you can instead make a Decisive attack that inflicts real damage, and resets your initiative (assuming it's still relevant). The damage of a Decisive attack depends solely on initiative - armor, weapons, and all that stuff matter for withering attacks, but not for decisive ones (which is a little weird, but there it is). Alternately, there are a number of Gambits you can perform instead of a Decisive attack - if you want to push someone around, or grapple them, or disarm them, that requires a Gambit.