That duelling move is cool but for something that epic, why not make a move that's a bit more detailed and dramatic?
Like:
When two characters are duelling to the death,
Answer the following questions for your character. The MC will answer for NPCs.
Are you ready to die? If yes, hold 1.
If any player doubts your word on this, say what you will to convince them. If they still doubt you, don't hold 1.
Are you free of remorse or hesitation to kill? If yes, hold 1.
If any player doubts your word on this, say what you will to convince them. If they still doubt you, don't hold 1.
Are you completely calm within yourself, free from self-doubt? If yes, hold 1.
If any player doubts your word on this, say what you will to convince them. If they still doubt you, don't hold 1.
At the moment of the clash, spend your hold. Whoever spends the most holds wins, and the loser is killed. If you spend the same amount of hold, roll a die to determine who wins, and the loser is given a terrible scar.
That's how I'd do it, anyhow. You could do a similar thing for archery.