Like ignore the mechanics of Halo ,the game, where marines eat dozens of plasma pistol rounds and react with voice clips like they scuffed their knee.
In the canon universe rules of Halo, single plasma pistol shots can take off limbs. One needle round can explode your torso.
Being unshielded in the story pretty much means you cannot get shot by covenant at all without dying or sustaining massive injury.
Spartans are as effective as they are because in the story, their shields can eat a lot of damage for them.



