Vasher and Denth's Climax
I wanted to offer Denth the chance for redemption here, though there was no way he was going to let himself take it. His response is honest. He doesn't feel he deserves it. He has done terrible things; to wipe away the memory of them would be cheating. Better to just get it over with.
There's a very good chance that after killing Vasher, Denth would have walked over, picked up Nightblood, and let the sword drain his life away. He wouldn't have been able to live with the guilt.
But that doesn't happen. When I first designed this magic system, I added to it the idea that taking a lot of Breath shocks you and sends you into a small seizure of pleasure. This is lifted from the magic system in Mythwalker, the story from which I drew Siri and Vivenna. I added the component to Awakening not only because it fit, but because I liked giving one more little nod to Mythwalker.
However, the moment I began writing it, I knew that this twist of giving someone Breath, then killing them, would be an awesome way to pull a reversal with the magic. So I built into the story the entire arc of Vasher beating Arsteel mysteriously, and Denth wanting to duel him to prove that he couldn't win a duel.
Denth was right. Vasher cheated.