Swords don't have the capacity to kill a human in one strike, It's very difficult to decapitate someone, As we learn from the French Revolution. With a gun, You just pull the trigger like a sissy and win immediately. The gun requires no skill, No ability. It's an easy way out for complete wusses.
Little children can use a gun right away. They just need one shot to win. A sword needs high force to cut. Plus you need to be faster than the other person and if you miss you will be open.
When the guns came out people were angry that any average man could beat people with years of training.
There are more instances where an untrained gunsman can win in a gun v. Gun duel with a Navy Seal than compared to an untrained swordsman v. Master swordsman. This means that to take down a master swordsman, You need to have more skill, Whereas you don't need skill to take down the Navy Seal.
Let me ask you something:Is a F1 driver any less skilled just because he races with a car, And not a bicycle? Why doing something but harder take any less skill. After all, A true modern gunfight, Separated from the category of quickdraws, Takes at least as much skill as slicing people in half with a sword. I'll give you a point on the fact that a gun duel at about a 15 pace distance isn't any more complex than a who shoots first fight, But guns have changed a lot recently. If you are within spitting distance against an armed enemy, Something went horriblywrong. But that is about the range for a sword fight. . . Your enemy is like, Right there, YOU CAN SEE HIM. Try sitting at a distance of about 100-150 meters and try to pick out and get a shot on your enemy. It ain't that easy anymore is it. You need to learn your stance(the way you sit when you shot), Finding cover(basically your guard in fighting terms)and most importantly not to sit in the same place for too long. And when you take two equally equipped men and put them about a football field apart, You can't tell me that a guy with a significant lack of skill can win. But then again, Guns were not made for fairfights, Just like swords, Bows and arrows, Or any weapon for that matter. . But it is what it is
I feel that it depends on what sword or gun you would be using. Of course this is just one of the variables. What if you were in an are with a lot of pedestrians around, Lets say the city. It would be hard to shoot your opponent with a lot of obstructions in the way also i feel that people underestimate how hard it is to shoot a gun from long range. Also the sword is actually not as hard to learn as some people think. Take this from somebody who is somewhat interest in kendo and other sword arts commonly used. You would only need to learn a few moves before you get the hang of it. After that it is just how hard you can swing the sword etc. On the other hand a gun requires skill to learn how aim and avoid recoil among other things. In general they depend on what type of sword and what type of gun. If the gun was a sniper and the sword was a rapier the gun vs gun sniper fight would easily require more skill while the rapier fight would be a lot easier in comparison. This goes the same way if you were using a harder sword to master. So in conclusion i think this debate lacks a few variables for the duels that would happen in order to make a proper answer.