I view Noble Six as Achilles. He was the UNSC's mightiest warrior, but in the end, he died, letting his arrogance get the best of him. The Field Marshall is symbolic of Hektor, the Covenant's deadliest warrior at that time. Six defeated Hektor, yes, but his brother(s) in the end avenged his death, and killed Six/Achilles.
The same could be said for Master Chief being symbolic of Aeneid, or Odysseus, and his travels, with his AI companion Cortana symbolic of Hermes or Circe.