Fire Emblem - Ankokuryuu to Hikari no Ken Manga

A century after the Shadow Dragon Medeus is defeated, he returns to threaten the continent of Archanea once more. In the distant past, a young hero from Altea wielded a divine blade to break Medeus’s rule and bring peace to the land. Now Medeus has joined forces with a sorcerer who seeks to rule the world, and together they bring kingdom after kingdom under their power. Altea’s king, the only descendant of the dragon-slaying hero, sets out with the divine blade to confront the danger. His son, Prince Marth, stays behind with his mother, elder sister, and a garrison from neighboring Gra, an ally of Altea. Marth studies both literature and swordsmanship until one day, events change his life.