GrimCo
Hero
There was change from 2e Thief to 3.x Rogue. While thief was supposed to be next to wizard far in the back, rogue was more like a mix of light nimble combatant who was intended to get into melee. As i said, unless you went Improved Critical feat (and rogues didn't get to many feats, plus, you burned one for Weapon Finesse) or you were lucky to get your hands on keen rapier, short sword was go to option. Same damage, 5% less chance for potential crit, same crit multiplier. Elven thinblade was Exotic weapon (so again, need a feat for it) and it's finessable long sword with 5% more potential crit chance. Most rogues (and i played mostly rogues and bards in 3e) used shortswords and daggers cause burning 1-2 extra feats was too much, specially if you went two weapon fighting route. Even with level or two of fighter, feats were tight resource not to squander lightly. That's why we also got chain shirt as light armor in 3.x.So basically, if you were a rogue, the best options were a rapier, or a more rapier-y rapier. That's part of what threw me into this chain of thought. I previously envisioned rogues using mostly short swords, or depending on the edition, maybe a long sword, or maybe they have a variant trait that gives them more martial weapons. But with 3e they turned into Errol Flynn.
Someone said rapiers started with AD&D... I looked it up, they are not in the 2e PHB. Any rapier-type weapon, presumably a 15th century transition weapon, would probably be a "long sword," two words, a Shakespearean-era designation for a typical, one-handed arming sword of any length. DMG 2.5 also does not describe rapiers, and does not mention them in the Renaissance equipment lists, only "early guns." I know they appeared in A Mighty Fortress, which had several fencing proficiencies, in fact.
Obviously, in a fantasy world, this comes down to preference, but from an aesthetic standpoint, most of the weapons are 12th to 15th century, not modern, like a rapier. Flintlock guns (barely) predate the rapier. I've seen anime shows where they have warriors and mages and dragons and such, but they also have bubble tea and cat clocks, which I am fine with as it's own thing, but I don't think of as the usual genre for D&D. But maybe I've just gotten too old, and rapiers and flying ships and clockwork cannons are pretty standard for this type of fantasy now.
Aesthetic wise, D&D is all over the place, mixing weapons and armors from different eras and cultures.
Best thing is, take mechanics and fluff it in a way you like it. Most groups i know did just that.