I'm not going to get into politics here, but simply point out some facts. In the past, the main cause for calling a duel was ...
Wrong: it wasn't over a lady (much as we'd like to think so). Historically, the main cause for a duel was if someone called you a liar.
In the seventeenth century, "liar" was a fighting word.
Apparently this happened often, for dueling killed off a shocking number of the aristocratic male youth during the 17th century. It was often outlawed — punishable by death in 1651 in France by Louis XIV, for example — but that didn't stop the boys. In France alone, over a 21-year period, 10,000 gentlemen died fighting for their honor. (One had to be a member of the aristocracy to qualify for the honor of fighting for your honor.)
In the early 17th century, the weapon of choice was the rapier, a long, heavy sword (heavier than modern cavalry sabres). Mid-century, blades got shorter and lighter, and with a sharper point. This favored the thrust, rather than the cut, which changed the dueling style. To protect the fingers, the cup hilt was created. A fight was often resolved with the use of a secondary weapon: a dagger.
(The advent of the pistol, of course, changed everything. No longer was the duel up close and personal — no longer could you see your adversary's eyes. Also, sword dueling allowed for fewer fatalities. You could ward off a thrust, but the only way to protect yourself from a man holding a gun was to shoot him.)
La Maupin (Julie d'Aubigny), a French cross-dressing opera singer, was a famous hot-tempered dueler. Her lover, a fencing master, taught her how to wield a sword. Apparently she was a good student. One night, after insulting a lady at a ball, she was told to leave by the lady's male friends. She agreed, but only if the men would go outside and fight. They did, and — according to legend — she killed them all and returned to the ball.
An excellent book on dueling is Gentlemen's Blood; A History of Dueling, from Swords at Dawn to Pistols at Dusk by Barbara Holland.
For a good website on the history of dueling: click here.
For an informative website on La Maupin: click here.