Koyu may be the youngest of the Lampdragon bandit heads, but that's no reason to think him weak. After all, not only was the young bandit pivotal in bringing Tinto under the Dunan Unification Army's cause when he brought news about Neclord's attack to Riou, but he was also able to infiltrate Neclord's hideaway on his own to rescue his sister and little Lilly Pendragon (Well, Marlowe was with him, but bookish NPCs don't count). While it's true that he's not as good as his elder siblings, the harsh life of a bandit means he still knows how to wield a mean axe, and the softer life of a duelist has hardly made his skills with it rusty.