[aesir23]

Generally, duels in history were fought with weapons that were actually in use, either for self-defense or in war. (The notable exceptions being some of the specialized dueling swords of the 19th century, like the Epee du Combat--but that was clearly a legacy from when swords were carried in public and useful in self-defense).

One of the purposes of the duel is to prove your courage, honor, and formidability. Courage and honor are demonstrated by showing up and risking your life, formidability is demonstrated by winning a fight with a culturally significant or useful weapon.

I imagine in the future, these reasons would remain. Soldiers would duel with a weapon they use in war (probably a secondary weapon or side arm, though to decrease lethality somewhat). Civilians would likely duel with a weapon they carry regularly and could use in self-defense.

In both cases, that might mean duels fought unarmed, but there would have to be strong cultural reasons to use an extremely specialized weapon with no use outside of dueling.