phalanx

[gamegeek2]

An arrow falling from a volley does not have nearly as much impact as straight shots do, and one glance off of anything makes it lose most of its effectiveness, as Aemilius says. Also, think of the helmets. An arrow falling gets blocked by a helmet much of the time, and the shoulder pads are reinforced. The most likely chance is to fall at about a 45 degree angle and hope that it can penetrate the linothorax. Also, the Persian bows were made of cheap, lower quality wood that was readily available to the massive peasantry of the Empire, and this reduced the firing power of the bow, which allowed Greek troops to time and time again ward off Persian arrows with superior armour.

Also I'd like to point out that, in movies, armour almost has no effect whatsoever, and a peasant with a crude weapon is often easily able to kill a prepared man in armour. This is easily explainable with an axe or similar weapon, but not with a crudely fashioned spear.

Compensating with defense skill sound like a good solution, but (WARNING!) it is kind of ahistorical; phalanxes didn't rely on defensive skill as much as the support of your comrades; training for individual combat was probably minimized in favour of discipline and practice in quickly forming ranks or the formation itself.