It was also not uncommon for either or both combatants to simply fire their pistols into the air. Again, honor was generally deemed to be satisfied if this happened. This took some courage if you were the first one to fire into the air, as you were still required under the code to stand there and let the other guy take a shot at you if he so chose.
I'd guess the big danger for duelists would have been damage to internal organs or deep wounds becoming infected. Bullets could do this, as could the smallsword, a purely thrusting weapon which would have been the sword used in the 18th century. McBane (https://en.wikipedia.org/wiki/Donald_McBane) wrote of the difference between cutting and thrusting swords "the smallsword kills, yet you might take fifty cuts and not be disabled".
If McBane was telling the truth he certainly managed to get away with a large number of duels, though.