“The man gasped agonizedly and went to his knees, but his tall mate lunged in, in ferocious silence, raining blow on blow so furiously that Valeria had no opportunity to counter. She stepped back coolly, parrying the strokes and watching for her chance to thrust home. He could not long keep up that flailing whirlwind. His arm would tire, his wind would fail; he would weaken, falter, and then her blade would slide smoothly into his heart.”
— Red Nails by Robert E. Howard, 1936
What if you could burn hit points to get an attack bonus for one mêlee attack? How much would you burn? 1 hit point? 2 hit points?
What if you could burn hit points to get a damage bonus for one hit with a mêlee weapon? How much would you burn? 2 hit points? 4 hit points?
What if you could burn hit points to get an additional attack that round with a mêlee weapon, subject to a maximum no. of total attacks that round equal to your level? 2 hit points? 4 hit points?
What if you could burn hit points to improve your AC against a single attack (mêlee or missile)? How many hit points would you burn? 1 hit point? 2 hit points?
What if special combat manœuvres such as disarm, knockdown, bullrush, et cetera cost hit points instead of coming free at certain levels?
In this way, players can make tactical choices of whether or not to play it safe or try to end a combat quickly.
After all, hit points represent stamina and luck as well as combat skill.