regarding Achilles

I’ve heard it takes a while to get to level 5, but no mention of the number of kills for each level

it might help if you where in a spartan company

Go check out Partyupgaming, Whiskey, or The Sauna. Look at their commendations, maybe that will shed some light.

The last level requires 486,000 Spartan kills.

you need to be in a spartan company