Stated several times in Grimoire cards and Dinklebot that Ghosts can spend all of their lives looking for the perfect candidate to be a Guardian. They're not stupid, they won't rez a little girl or an old man, but a battle-hardened soldier(probably). Mars Grimoire states the Ghost went there because Mars attracted the clever, brave, and who want to prove themselves. We were found at the gates of the Cosmodrome, probably had taken on hordes of Fallen. So that matches your 'picked from 6 & augmented'. We were picked from a lifetime of heroic qualities, and gifted SUPERHUMAN powers. Not some bullshit Spartan augmentation. Actual space fricken magic, from a giant ball of light in the sky. Ability to rez, self-rez, blade dance, golden gun, erm Radiance? Hulk smash. The warlock melee alone could probably take out most Spartans lol. Blink to them and punch them into void dust. Easy So we are strong, clever, imbued with superhuman space magic, have an AI with us (which while in story is a dumbass, sorry Dinklebot, but in reality is an AI. Just as good as in halo) and lastly let's not forget about our weapons and armour. Our arsenal is made with magic, just like us. Thorn, Bad Juju, Icebreaker, Ghorn, Red Death. Heart of Praxic Fire, you turn into a sun and throw balls of death at an extraordinarily rate. Sorry Spartans, die to fire