Some of the 3+ ft weapons might be covered by the scimitar, or shortswords pushing into rapier category, but most would be 5e longswords. The shorter ones are less optimised towards two-handed capability; as the length of the weapon pushes towards 4ftish, designs generally become more optimised for two-handed use.The Japanese measure blade length by foot.
The length of D&D blades correspond as follows.
• 0+ feet: dagger
• 1+ foot: shortsword
• 2+ feet: ?
• 3+ feet: longsword
• 4+ feet: greatsword
The sword that is missing in D&D is actually the important one: viking sword, knightly sword, spatha, katana, etcetera.
I'd personally say that the actual design of the sword matters, and styles of use vary considerably rather than being able to give a straight answer comparing 'single-edged' vs 'double edged'. The katana and falchion/messer feel similar in the hand for example, but actual design and styles of use are very different.If there are any historical swordfighters among us, what is the main difference in feel between a single-edged sword and a double-edged sword?
D&D Blades
• (0+ feet) Dagger
• (1+ foot) Shortsword
• (2+ feet) Sword
• (3+ feet) Longsword
• (4+ feet) Greatsword
is this the lenght of the blade only or whole weapon?
Turns out Tavern Brawler doesn't even need to be adjusted for it to work with a longsword.
"In many cases, an improvised weapon is similar
to an actual weapon and can be treated as such. For
example, a table leg is akin to a club. At the DM’s option,
a character proficient with a weapon can use a similar
object as if it were that weapon and use his or her
proficiency bonus."
[MENTION=6802553]BookBarbarian[/MENTION] : No toes stepped on at all.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.