Sorry for the stupid question, but what actually is a longsword? Is it a sword intended for 2 handed use but can be used with 1? Most rpg games have longswords classified as 1 handed weapons, but from what i’ve read on the internet a longsword is supposed to be mainly 2 handed.
That’s not a stupid question, it’s reasonable confusion based on some idiosyncratic classifications created centuries after the weapons saw use. The very simple answer is, the longsword was “a sword.” Most of the specialized names for swords, particularly anything ending in “sword,” is probably a modern classification which doesn’t fully reflect the weapon in question.
Historically you wouldn’t have described your weapon as a longsword, it would have simply been your sword. A lot of the modern terms like longsword, shortsword, bastardsword, greatsword, broadsword, arming sword, and so on are exactly that: modern. Many of these terms only date back to the 19th century, when antiquarians were attempting to classify swords into very specific categories.
In some cases, these categories accurately reflect weapons that existed, and can give you a quick shorthand to understand what the weapon was, and how you used it. For example, “shortsword” and “greatsword” are useful terms. They describe distinct classes of swords that existed historically. That said, the edges are a bit, “fuzzy.” For example, determining when a knife becomes a shortsword isn’t an exact science. There’s no specific length where you can say, “nope, no longer a knife, now it’s a shortsword.” How the weapon was used can help to inform what you want to call it, but these are not hard and fast rules. Your shortsword may be a long knife to someone else.
To expand on this, something like an executioner’s sword is a useful name, because it refers to the function of the weapon, and it has a distinct stylistic element that makes it easy to identify and distinguish (in this case, a flat end instead of a sharpened tip.) There are also plenty of weapons that incorporate distinct elements which make them unique. Another example would be the estoc, which has a mostly unsharpened blade, but boasts a very sharp tip, primarily for piercing the joints of plate armor.
So, there’s three specific examples I should probably expand a bit, because you’ll run across them all the time in RPGs and other media, the Longsword (which you asked about), the bastard sword (which you asked about incidentally) and the greatsword.
A longsword can be anything from a Viking era iron blade, up through to some small two-handers. Usually defined as having a straight blade, these cover dozens of distinct sword designs, which popped up in Europe over nearly a millennia. Because the term is so diverse, there’s really no one “true” longsword, even in popular media. Even within a single game you may see weapons ranging from 8th century one-handed swords next to 15th century two-handed longswords. Usually games will present these as weapons you can wield one-handed, though even this is a bit misleading as most greatswords can be wielded with one hand, at the cost of some finesse and efficiency.
Bastard Swords are… something. There’s no certainty on what the term meant historically, and unlike some other names kicking around, bastard sword was a historical term. The modern meaning of a bastard sword is (usually) a longsword blade with a greatsword grip. That’s, basically, fantasy. Swords like that did exist, but they weren’t considered a unique class of blades until the 19th century.
Greatswords are a modern weapon (though, in this case I do mean early modern, so 15th to 16th century.) The actual names vary by culture of origin. There’s something of a theme here, with most cultures naming their greatswords some variation of “big” or “large” and “sword.” The German Zweihander is a minor departure, as that simply means, “two hands.” While I’m not completely certain, I think the term “greatsword” comes from the translation of Claymore. (Specifically from the Gaelic claidheamh mor.) Historically, the greatsword fell out of use as European armies transitioned to longer polearms, and by the 17th century, firearms were becoming an increasingly important part of warfare, so these enjoyed a brief moment before disappearing.
It’s probably also worth remembering that swords are very light weight. A 4lb longsword would be heavy, most ran 2 to 3lbs. With two-handers the norm was slightly under 8lbs. Substantial for a weapon, but not heavy to the point that you’d be unable to lift it with ease. Real world swords have (basically) never been about overall weight, so much as finesse. This is part of why I said earlier that you can wield a greatsword with one hand. It wouldn’t be as effective, but you could still maneuver the blade. The entire point was to open your opponent up, usually by finding vulnerable points and then exploiting those. This is part of why Europe transitioned to lighter, faster, blades, which could get in and out quickly. It’s also why weapons like the Estoc existed at all. Allowing the user far more control when they drove the tip through a joint in their foe’s armor.
Most swords can be used two handed. Even if your off hand won’t fit on the hilt, you can use your fingers to help control and direct your strikes. Even with larger swords like the zweihander, your off hand isn’t there to provide more strength, you use it to stabilize and guide your attacks.
A lot of games use longswords as one handed weapons because it’s easier and simpler. It provides the player with a clear delineation between that weapon and a two handed weapon class. You know, when you find one, what it will do and how you can use it. This is further reinforced in many video games, where you would need separate animation sets for wielding the weapon one handed vs two. In cases like this, there’s a real incentive to lock it into one mode and leave it there, especially if a two handed weapon class already exists.
So, the short answer would be: It’s a sword.