Endurance!
One of the interesting and often ignored rules of Classic Traveller was 'expending' points of Endurance to make melee attacks or sprint. CT was often about resource management. This rule was dropped from subsequent editions of the game. No one seemed to like it =I get six good shoots then I'm -3 to hit with my chainsaw? Something like that despite the fact that most people had a plethora of guns and could fire enough rounds to darken the sun. I don't want to suggest using Endurance/blows, I have no desire to be lynched. However, what if Endurance could be expended to allow extraordinary efforts? Reserving this for PCs or important NPCs would improve a group's odds of survival, especially if you're using old style simultaneous action turns. It will also give players an incentive to cut and run rather than engage in long running fights. Once their Endurance runs out, no more playing action hero. As with all combat, your Endurance score is not changed due to wound