An hoplite, circa. 450 BC.

Hoplites were supplying their own equipment, so the quality of the armor suggest that this is probably a nobleman and fights in the front row of the phalanx (the rear rows would wear much lighter armor). The colorful attire would help the members of the phalanx identify to another and avoid friendly fire. (As well as possibly intimidate the enemy.)

Later iterations of the hoplite would wear lighter armor with much less of the face being covered, making them more mobile and perceptive. However the Corinthian Helmet remained a popular icon among greek artisans and keeps showing up in depictions even after it fell out of military use.