I know it's not technically what it asks, but as a swordsman, I can tell you that a sword is worse than useless without an appropriate martial art to back it up. So having a sword in fiction is equivalent to having some amount of skill unless otherwise noted. An untrained swordsman can expect to cut themselves just as much, if not more, than the person they're fighting. The skills and the weapon are, in all practical senses, inseparable insofar as a character could be called a "swordsman". It's usually special cases where a character has a sword and a plot point includes them being unable to use it.
Otherwise, I can see swords being useful post-apocalypse or otherwise after industrial breakdown. Without industry, modern ammunition could no longer be produced in any significant quantity. A few years of maddened warfare, all the ammo goes kaput, alternative methods have to be found. More primitive firearms, crossbows and bows would probably fill the void very quickly — and, of course, close combat weapons of all kinds. Although this isn't "reality", it seems reasonable enough.
The essential thing to note is that time hasn't dulled the edges of other weapons. Something like a sword isn't practical in warfare, and not necessarily in self-defense in gun-heavy countries, but in other cases an approximation is the best thing available. For instance, in Australia, truly combat-effective guns are illegal for civilians to own. It's a part of what inspired me, personally, to take up swordsmanship. Against John Thug on the street, an umbrella or lucky metal pipe makes a fine sword, especially in the case of John Thug having his own improvised weapon of some kind.
Also, there's certainly machete fighting arts around. Particularly in South East Asia, if my memory recalls. In especially dense terrain, a light close combat weapon is more immediately practical, be that a knife, bludgeon, machete or whatever you choose.
In short, it comes down to what "having a sword" implies in a fictional sense. Plenty of people today own swords without having the capacity to fight with them, but fiction is different. If you have a sword, that's almost evidence of the ability to use it. So while running around with it is almost a uniformly bad idea, a character, say, having one at home can be a nod towards their skills.
This isn't an argument for the question being removed, just for the record. But what count as "impractical" isn't that clear-cut is all.
edited 18th Sep '11 2:51:30 AM by MadassAlex