User blog comment:Jackofalltrades9X/Enemies of the Holy War/@comment-124.83.31.223-20150916141956/@comment-124.83.31.223-20150918121802

【英雄】の一角とはいえ肉体を使った戦闘能力は低く、今年で齢八十を迎えた老人であるイムルスカ猊下の貧弱な肉体では、聖木製の円卓を叩いても歪ませる事すらできない.

This line right here seems to say that an [Eiyuu]'s ability for combat using their own physical body is low. Right after this, the Codex Great Hero's friend, the Hero (Yuusha) of Number Expression (not sure how to translate it), is introduced as being rather physically fit and powerful despite being the same age as the Codex Great Hero.

Considering the "Yu" (雄) for Eiyuu has a different meaning to the "Yu" (勇) for Yuusha, I don't think it's appropriate to translate Eiyuu as Great Hero. Yes, 雄 can mean hero, but it has the connotations of 'musculinity' and 'leadership' as well. Hence why I think Eiyuus are supposed to be military leaders. On the other end, 勇 means bravery and heroism. Not that, that can't be applied to military leaders as well, but it seems like there's a distinction between what traits each of the two characters emphasize.