User blog comment:Hyperborean/"The House of Hades" – official expectations blog/@comment-170.235.245.53-20130604183437/@comment-5112532-20130604184316

Luke didn't actually beat Ares. Instead, he persuaded him to listen to Kronos, who told him about the war that he had planned. Since Ares can't resist a good battle, he lets Luke take the lightning bolt. Although, Kronos is much more powerful than Ares so he may have been very good at persuading Ares.