Raidorl Seiken Senki

Raidor Zain is the second prince of the Kingdom of Zain. On the day he was chosen to bear the Holy Sword, the boy's destiny is set into motion. Exiled from the capital by his jealous older brother, Granard Zain, the boy spends his youth in the harsh remote frontier. There, he finds a little peace and happiness for himself. However, he finds himself caught up in the war with the neighboring Arslein Empire... Confronted with his brother's plot and the war over the holy sword, Radeor decides to "rebel"...

(Source: Ichijinsha Plus, translated)