Final Dead End!

After defeating the Demon Lord, one Hero left this statement on record: "If the Demon Lord were pure evil, then we wouldn't agonize this much over what we've done." The Hero and the Demon Lord, two who are destined to fight. However, if there were some justice to the Demon Lord's actions, then would the Heroes still be able to brandish their swords? And what on earth is the Final Dead End that holds the key to everything?