Battle starts with a spear through Magneto's masturbation hand (left or right?) Who win?
Actually...the spartans wore bronze armor, which is non-ferrous (not magnetic), so they would have a fighting chance.
Magneto doesn't need his hands to be able to crush them with their own armor. Nothing they do will be able to penetrate his force fields. Spite.
The only issue is most likely their other weapons were made of steel. So, they may be able to get close enough to do some damage, if not kill Magneto.