Can a sword cut through steel bars, or is that fantasy? Also, how much space is needed to use a sword correctly and is there a lot of difference between say, the space needed to use a long sword as opposed to a short sword? I’m guessing an enclosed space the size of a closet would suck. I’ve tried searching through your tags for an answer to this but didn’t find it.
For the first question, the short answer is no. There’s a full discussion to be had on metal hardness
As I said, there are a lot of relevant factors here as well, such as how easily the object will bend out of the way, but when you’re talking about trying to cut your way through a bar of metal, you’re going to need a lot more than just, “a sword.”
I should probably add, you also don’t simply hack through metal armor with a sword. It doesn’t matter how sharp the blade was when you started out, that kind of brute force will wreck the weapon. Instead, you’re looking for openings, which are necessary to allow the user to move.
This still applies for cutting through bars. While the bars and sword may have similar hardness as materials, the blade’s edge will be more fragile, and any attempt to simply hack your way through won’t end well for the sword.
When it comes to simply hacking through objects, you’re better off with an axe. Those are designed to deliver a lot of blunt force along the edge. You still shouldn’t expect much from taking a steel axe to steel bars, but it is better suited for that kind of abuse.
Now, if you’re using some kind of fantasy weapon, like an impossible blade that breaks down anything it connects with on a molecular level, like Warhammer 40k’s power weapons, or a lightsaber, then steel bars aren’t going to pose much of an obstacle. However, in cases like that, you’re not really concerned with how sharp it is.
Okay, back to the second question. There isn’t a concrete answer, because it will be determined by the sword and the techniques your character’s been trained in. It is entirely possible to use swords, even fairly large ones like the zweihander, in fairly tight quarters.
For a lot of European sword combat, the tip of the blade is the most important point of contact, so you’re more interested in linear thrusting strikes, rather than large slashing patterns.
Even when you are whipping the blade around, there’s still a major focus on being efficient with your motion (at least in most of the surviving schools of thought). There are still a few surviving manuscripts and approaches which focus on wider arcing strikes, which would require more space.
Remember, one major use for swords in Europe was in tight quarters while assaulting castles and fortresses. If the sword couldn’t be used in close, it wouldn’t have remained in use for long. This does mean that, sometimes, you need to get creative. There are a number of grips where you’ll control a sword with one hand on the blade (called half-handing, or half-swording), and others where you’ll strike someone with the pommel, which can be executed at much closer ranges.
With very few exceptions, you don’t wave your sword around in large telegraphed strikes unless you need to. It may look cool, but it’s far easier to defend against. Just like in hand-to-hand, exposing your movements to your opponent is something you want to avoid whenever possible. Keeping movement inside your silhouette makes it harder to track. With that said, the circular sword styles you’ll see in something like The Witcher 3 do have a basis in history, and those can work, for a trained practitioner on open ground.
Historically speaking, shortswords weren’t really a thing, sort of. Bladed weapons in the range of 12 to 24 inches existed, were, and are, real, but, like the greatsword or bastard sword the term is almost certainly modern.
Depending on the era, a shortsword would either be a sword, or a variant of knife. This has to do with the overall technological development. The Roman Gladius was a sword, but, turn the clock forward 1500 years, and a similar weapon would have been a knife or bayonet.
If it’s a sword, it’s probably a sidearm. An early iron era soldier would probably carry a spear or some other polearm as their primary weapon, with a backup sword if their primary weapon was lost or destroyed.
If it’s a knife, it’s probably a backup sidearm. An early modern solder, or even a soldier today, will likely carry a knife as an emergency backup should their primary weapon and sidearm fail, or if they need to use it in very tight quarters. For example, if a soldier was tackled to the ground, stabbing their opponent with a knife would be a legitimate option.
It’s probably worth mentioning, a smallsword is actually a rapier, epee, or another sword with a similar long, slender, blade. The name referred the weight of the blade, rather than it’s length.
Sideswords are another descriptive variation. These were longswords specifically intended for use as sidearms. Depending on the individual blade’s country of origin, these could also be a smallswords. They’re not so much a distinct kind of weapon, as a distinct use for one.
There’s an entire discussion to be had on how modern sword names actually make things more complicated than they need to be. The abbreviated version is: A lot of descriptive sword names come from the 18th or 19th century. They classify a lot of blades idiosyncratically. It’s where we get the modern meaning for terms like long sword, bastard sword, or short sword. Historically you would not have had “a short sword,” it would have simply been, “a sword,” or, “a knife.” There are a few more egregious examples, like the broadsword, which was never used historically. And, as I’ve mentioned, the term “bastard sword,” isn’t new, but on one knows what these referred to historically. This doesn’t mean you shouldn’t use those terms, just understand, most never really meant anything, historically.
So, in spite of not being a thing, short swords, or long knives, or bayonets, had a role as an emergency backup weapon. That, really hasn’t changed. The way you’d use a combat knife today is fairly similar to what they would have been used for eight-hundred years ago.