Let's talk about sword weight!
This is my longsword. It's 51 inches long, 38-inch blade. Leather wrapped hilt, scent-stopper pommel, unusual triple fuller. It's loosely based on the 15th century Oakeshott Type XVIIIb longsword, so it's basically a regular hand-and-a-half sword with an extra long hilt. Made by Szymon Chlebowski, a very talented Polish swordsmith. (It does not have a name, and I refuse to give it one, so don't ask!)
It's about 3.5lbs, and that puts it on the HEAVY side for a longsword.
First of all - yes, it is possible to hold it out straight in one hand. I do it all the time! But you can' t do it for longer than a minute before your arm starts burning like it's been dunked in lava. 3.5lbs doesn't seem like a lot, but holding it out like that is hard! It puts a huge strain on your bicep and forearm.
A 16th century Italian rapier is about 2.2lbs, and you have to hold that out for long periods of time in the various guards in one hand. I guarantee that your arm will start hurting like hell after just a few seconds if you're not used to that. I know mine was when I practiced with a rapier.
I've also used a much bigger longsword than this one. My other weapon of choice is a greatsword - a proper two-hander that weighs about 4.5lbs. and almost comes up to my shoulder. I can hold that out in one hand for, oh, maybe ten seconds.
Movie replica swords though...
See, much as I'd love a copy of Aragorn's sword from LOTR, it's literally not possible to get one that's functional because they're too big and too damn heavy! United Cutlery makes the officially licensed versions from the movies, and even if they could be used in combat (they can't, they're all stainless steel) they are far, far too heavy.
Take a look at this Anduril, for example. It's an inch longer than my sword, and it's over 5lbs! I couldn't wield it, and I've been doing longsword practice for almost a year.
Gandalf's sword, Glamdring, a little lighter but still way too heavy at 4lb 9oz.
How about Eddard Stark's sword from A Game of Thrones? That's about the size of the greatsword I've used frequently, and it's almost TWICE the weight.
Okay, okay, these are replicas. Not meant to be real swords, etc. But dayum... swords do not have to be this heavy, and I keep seeing the myth of the very heavy longsword popping up in movies and books. Most swords were light, guys. They HAD to be, if you're going into combat with them all day.
I mean, just think about it.
Why should a sword be heavy? Medieval swordsmiths were not stupid, and by all accounts they were making some really fantastically good steel. So the blades were hella strong even if they were light. That fuller I described earlier (which is the groove down the middle of the blade) isn't just for show! It makes the blade much stronger and more rigid without needing extra material. The crossguard is thin, because it's also made of good, light steel.
Take a look at these zweihanders - some of the biggest swords ever made for actual combat use, so big that they were more like polearms than swords.
Notice how thin they are, how they seem almost delicate. These are the real deal, believe me, and they'd kill an opponent very effectively. The idea of a longsword, or a greatsword, being this huge, lumbering tree-trunk-shaped hunk of metal is silly. Swords were never made like that because they never needed to be, and it was much more practical for a 6ft tall human to have a lighter sword.
I mean, you can't scale up the physics of effective swordplay and still expect it to work. It just doesn't. There are rules about how much strength you need to accelerate mass through space while still maintaining enough friction not to fall over. Once again, Skallagrim did a great video on the math involved using the Buster Sword from Final Fantasy as an example, and the verdict was that it was flat out impossible to move a sword that big! The worst part is you'd still likely die to someone wielding a normal sword of normal weight, because, all else being equal, a bigger, heavier sword is going to move slower. That is a huge, insurmountable handicap in a fight to the death.
As a longsword fighter, this has to be in the top ten things that annoy me. Fighting with big swords was not like fighting with metal fence posts, people. Quit putting big dumb swords in your books and movies!
(Rant over, sorry :P)