I guess it depends on a lot of factors. In the Robin Hood tales. a stout oaken staff makes an excellent defense and attack weapon against any sword or foil. Whack the guy’s shoulder with a big stick and he cannot use his sword with that arm. Whack him hard, upside the head, and game over. A helm cannot protect you from a broken neck. A horsewhip or bullwhip can be deployed at a distance much longer than a swordsman’s reach to very good effect. Likewise, a net of chains wielded properly can render a sword useless for just the few moments it takes to put the swordsman in a head lock with an itty-bitty knife poised over his adam’s apple.

Farming folk are not usually equipped with costly swords of the type the upper classes use for ‘honorable’ combat. They are described as carrying billhooks, dungforks, axes, hatchets, and the like. Even a sanitary trench-digging spade can become a weapon during a sneak attack on the supply train or baggage wagons where the boys tend the fires and cook the troops’ meal.

Infantry are usually equipped with pikes and lances either steel tipped or all-steel tubes. In a pinch, fire-hardened bamboo or fire sharpened hoardings from the castle or a broken palisade can be used to form an anti-calvary square. Or if they are yeomen, they have longbows and/or crossbows.

Native Americans carried various dual purpose blades such as short fat-bladed knives suitable for close in-fighting, hide/leather working, meat processing, root-digging, and camp cooking. Stone hatchets likewise build shelters, make kindling, and crack enemy skulls. Long slender fish knives are good for sneak attacks from behind in the dark.

Glass edges and porcelain knives undetectable by metal sniffers or magnets can be concealed inside elaborate hairdos of dancing girls and other entertainers. Even pencils, nail scissors, and knitting needles can be used by a determined defender, especially if the attacker has been partly disabled by drink or drugs beforehand. For that purpose, a tiny thumbtack and a hit of curare might be all the edge you need. Blowpipes, beestings, and attack dogs are other methods of defense that a sword fighter might find difficult to counteract.

For that matter, the old pepper up the nose or flour tossed in the eyes trick is not to be despised. That’s how Robin Hood got a drubbing from the miller he messed with once upon a time.

As a practitioner of European martial arts you can count on me for more information, a very interesting manual that also includes many martial techniques is opera nova by Achille Marozzo (https://wiktenauer.com/wiki/Achille_Marozzo)

There are also some modern novels written by some Hema practitioner. for example( https://www.goodreads.com/book/show/28593206-the-talhoffer-society)

In addition to knightly martial arts, I also practice European knife martial arts as well as a Basque shepherd's cane (https://www.youtube.com/watch?v=js6lws5KCvk&list=PL_ZEWQpYs47bXaRY0PJ3si...)

Good point (haha) about swords and other sharp implements, though black powder for muzzle loaders is not that difficult to make in a low tech environment. Percussion caps are nice in wet climates and despite your contention above, do not require much beyond sheet copper and fulminate of mercury. They were developed in the 1820's... And flintlocks are even lower tech, though frustrating to use in wet conditions or for repeat shots. I have always been an archer and make wooden bows myself, so my characters tend toward bows and arrows. Also a good choice for females or non-Conan size males.

I have a Civil War era replica pistol that is cap and ball and learning to load, shoot and clean it has been quite enjoyable. There is also no permit or license required to purchase black powder cap and ball firearms, at least in my state. In fact, you can get black powder delivered to your door by UPS. An adult has to sign for it but other than that and a volume limit per package, it's a great way to have a VERY effective firearm that is not on any registry and doesn't require purchased ammo. I currently buy ready made .45 caliber lead balls but I am hoping to learn to cast my own. As far as caps, I bought a couple cans of 100 and figure that's plenty for my lifetime.

In my Ice Free Earth series, bronze Saker cannons figure prominently for defense against raiders and onboard larger ships. One of my premises in that series is that steel manufacturing is intensive and complex and that over the 500+ years since most iron/steel was produced, it has mostly rusted into uselessness. Think about how many iron implements you know of that are 500 years old...

Bronze on the other hand is more easily cast and worked and has many advantages over iron. Steel is a whole other thing from iron and I doubt that many places will retain the ability to make quality steel other than perhaps from rare non-corroded salvaged metal. Essentially I am proposing a new Bronze Age, both for technological/economic reasons and for resiliency/sustainability. Bronze does require tin in addition to the copper base (and of course there are other metals (silicon, molybdenum, zinc, etc.) that can change the quality of the bronze significantly, depending on it's purpose). I can't bring myself to consider bronze cannonballs though, considering the high value of the metal. So my people use stone, laboriously pecked into balls and I am toying with the idea of glass cannonballs or at least using glass casting shards as grapeshot... Think a glass cannonball would work?

As far as sword fights, my characters are not skilled swordsmen, more like village boys, craftsmen and farmers, so violent scenes are mostly chaotic, fast and (hopefully) frightening. The tension prior to and following the actual physical violence or avoidance of same, is where my interest goes. In my stories I'm looking to present violence in a way more akin to actual combat, rather than Dumas' style elegance with a rapier... Not to say I don't like reading Dumas or Patrick O'Brian! But that's not how I want to present warfare/violence in my books.

I did two years of rapier combat with the SCA. That was fun, and much easier to cope with as a small female teenager than full armor, broadsword and shield. I didn't have the mass to make the latter work.

Rapiers, cavalry sabers, and small swords were in-use well into the gun era. They all work much better on unarmored than on armored foes. Given that bullets can punch through armor that is light enough to fight in, I do not expect full armor to make a comeback in the foreseeable future, and the swords seen will likely assume that your foe is not wearing armor.

Then again, how hard is kevlar to make with low technology? And can a lunge with a sword stab through it? I know little about kevlar; it's out of period.

So probably something that would be difficult/impossible to get most places/times during the next dark age. Thought so, but knew nothing about kevlar. It's not something you learn much about in the SCA! Which means that sword usefulness and design doesn't need to take kevlar into account, and you can likely assume an unarmored opponent.

Slashing strokes are much, much easier to ward off than a lunge with the point of the sword. There's a lot of force behind that point, even if there's a rubber bung on the end and you're wearing protective gear. You learn to pull your strikes so you don't hurt your opponent by accident. Did the spanish start using the cloth armor against troops using metal weapons and guns, or only against stone and wood weapons that the Aztecs and Incas had when the Spanish arrived? That might tell you a lot about how well it would work out in a future dark age scenario with fairly widespread gun use.