After Nanahuatzin flew into the sun to give it life, he emerged from his sacrifice as an eagle. Thus Aztec Eagle Warriors were warriors of the Sun. 
While the ranks of Aztec military consisted mostly of commoners, through bravery and feats of strength on the battlefield a soldier could rise to join the noble society of Eagle Warriors. Feared for their extraordinary combat skills, they wore distinguishing armor decorated with feathers and heads of eagles with an open beaks headgear