Great article on dual verses duel
Schlager swords were popular in Renaissance German duels.
Commonly confused words is always a challenge for a writer. So I am pleased to re-post the above link that clarifies the difference between dual (two) and duel (a personal battle between generally two or a few combatants).
What is really interesting to me as a writer is that duel is from a variation of “bellum” meaning “war” — as in the Anti-bellum era of American History; that is, the 19th century decades leading up to the American Civil War.
So as your dual nobles duel to the death with rapiers, remember to associate “duel” with war and you will be just fine.