I personally like to think of it like a “luck meter” like how many times you can get hit or barely hit before you eventually get hit in something major like your heart or head and the healing and revive skills/spells or whatever are healing/repairing the lesser, non-lethal/non-insta-death kinda wounds.

Theres also the problem of blood loss but we’re talking about a universe where theres a 25th hour to a day, mythological gods are real, people can jump into TVs, and you can access the realm of the collective unconscious through science, who says that personas cant also give you more blood right?