The ones with armor were the ruling class: the rich landowners who could buy proper weapons and armor and who regarded military service the way their modern counterparts regard the local country club. War was an excuse to pal around with the guys, steal shit, and earn status while driving the landless and poorly equipped men into the fray first. That general mentality persisted all the way up through the creation of professional standing armies, with aristocrats buying commissions for their failsons the way they get them jobs as journalists or think tank wonks today.

Power and being a big strong violence man were inextricably linked for most of western history, even when that boiled down to sitting on a horse in a nigh-impenetrable suit of armor and massacring barely armed civilians in a raiding party because your cousin called you a punk so you have to go kill his serfs for a few weeks, or sitting in a canvas tent far behind the lines coming up with the dumbest ideas anyone had yet conceived of.

Hell, one of the funniest things about Sparta is that because they so closely tied land ownership to being a soldier (specifically someone had to be rich enough to hang around the country club all day with the guys instead of working) that they had to do land redistribution multiple times because capital consolidation made too much of their warrior class ineligible to serve.