The big thing about historical Earth dueling (European tradition) is that it's risky and potentially highly likely to be fatal.

There's a transition in civil weaponry in the 1500s from primarily cutting swords to primarily stabbing swords (rapiers and their kin).

Cutting wounds tend to be peripheral and survivable.  Stabbing wounds, to the head, and the torso, particularly those that penetrate the GI tract, tend to be much less survivable, particularly without surgery, anesthesia, and antibiotics.  The reason dueling gets outlawed throughout Europe as civil society transitions from cutting to stabbing high fatality rate for stab wounds.

This is less of a problem for modern societies with better surgery, antibiotics, etc., but a stab wound (or puncture wound for bullets) is still painful and risky.  Modern medicine may be able to save your life, but it's still damn inconvenient to have extra holes in your lungs, kidneys, liver, GI tract, etc.  

Modern 3 weapon Olympic fencing is an extremely sanitized and sporterized version of rapier combat, designed to simulate (sort of) real fights, while making it relatively hard to intentionally injure an opponent.

Dueling with single-shot black powder pistols is risky.  The weapons are still somewhat unreliable.  If they are smoothbores, they may not be terribly accurate.  You only get one shot.  If you hurry and try and beat your partner's shot, and miss, they have the rest of your life to aim and fire.  The weapon might misfire. (Potentially, depending on the rules, if you *both* miss, you either call it a day, or reload and try again.)  Bullet injuries can be pretty horrible, depending on bore size, bullet weight, powder load, etc. Both parties may end up maimed or dead. 

 

Dueling is largely driven by social pressure.  

There is something of an incidence/consequence matrix.

High incidence/High consequence:

Dueling cultures that have a high rate of incidence of duels would tend have a highly developed sense of personal honor, possibly exaggeratedly so, depending on the likely physical consequences of the duel. The fear (or social consequences)  of being seen as a coward for declining a duel has to outweigh the fear of getting maimed or killed in a duel for that sort of thing to continue.

High incidence/Low consequence:

Sometimes, dueling is a social status thing, a rite of passage.
https://en.wikipedia.org/wiki/Dueling_scar

Professional dueling may fall in here, too, if people commonly hire someone else to fight their duels for them.  This might include judicial duels, too, where "fate defends the right".  If there are judicial duels, there may be rules in place to balance things one way or the other, depending on the case. 

Low incidence:

Legal (or not) but rare, because most people have other, less personally risky methods of solving their problems.  It may be seen as "quaint" 

Depending on the culture, and the risks, dueling may be a huge game of chicken, where the primary goal is to shame the other person, make the other person back down when threatened, or make them chicken and not show for the duel, because the social injury is more useful than physical injury.  A lot of challenges may be resolved at the last minute, when both parties are looking at the swords, or pistols, or whatever, and deciding that maybe it would be prudent to apologize (or accept an apology) rather than risk getting maimed or killed. Saving face becomes an important, delicate art, and the ability of your seconds to negotiate a settlement that keeps either party from being embarrased becomes more important.

In addition to culture, the frequency and severity of duels will will depend on weapons technology and medical technology.  Safety measures can be built in to the system (light armor to protect vital areas, weapons designed to make it harder to kill someone, rules designed to make it harder to kill someone, etc.) but even so, accidents happen.

(Again, so a guy get an accidental broken rib while fencing.  I know a guy who's shoulder got dislocated in a close engagement.)

Another thing to consider is how much someone's social circles interlock and overlap, and how much blowback is likely if someone is seen as picking unjustified fights, or using excessive force (however the locals define it.)

For example, A picks an unjustified fight with B, and gives B a more serious injury than the offense warrants.  B's friends C, D, E, F and G all start looking for excuses to pick a fight with A.  Or B's friends take up a collection, and hire a professional duelist to pick a fight with A, paying the professional to inflict a more severe injury on A similar to the one A gave B.

Just some thoughts.

Dan

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