In relation to the universe and the first game, the Master Chief did impossible shit in Halo 2 and Halo 3 that would have killed regular Spartans. Hell, why do you think most of them are dead (besides the ones that got glassed on the surface of Reach)? The Master chief jumping off that forerunner ship in the atmosphere at the end of H2/start of H3 and landing alive without jump gear? What the fuck? Spartans that jumped out of a pelican with less speed and distance to the surface than Master Chief hit Reach and died instantly. I don't believe that a simple change from Mark V to Mark VI armour allowed the Master Chief to just get up and walk away from his landing.