The majority of warriors in the High Elven armies are citizens rather than professional soldiers. This militia is a form of the part-time army in which all take their turn to serve, every Elf providing his own battle gear in defense of his home and country.
As his familiarity with the horrors of battle grows, he will eventually be promoted from Archer to Spearman. This is the senior arm of the militia and he's expected to fight bravely in the main line of battle. With decades of experience behind him, an Elf can don the armor of the Spearmen and join his fellows in the rigorous training needed to fight efficiently as one body.