The spartans would in all likelihood would pick up the enemy baneblades, thunderhawks and start wielding them as melee weapons against the astartes,
Is that while they are also launching fire balls from their asses?
Seriously do you even read the "facts" (read that as bollacks) you post? A spartan who is what 8 foot tall if going to wield a thunderhawk which is over 26 meters long as a melee weapon?
That explains why a punch from a Spartan sends a grunt flying into outer atmosphere then...