warfare changed during the time

no longer were armies proffesionally made with simple units and standards
but now its a bunch of peasents trained into soldiers by their lords who owned fiefs of lands or loyal to a certain leader. These men would have had huge treasuries from loots, campaigns, or taxing their lands and certainlly would want to appear stronger and richer than his rivals by having his soldiers well armed and armored...

by this time, if im not mistaken, armor was in fact widespread and javelins were not used as much as before due to the fact that he could be struck down by a crossbow quickly and it prolly wouldnt pennetrate the armor of the knights etc..