When I mean "History" I'm counting fiction too, who in all that you've read, is the MOST skilled swordsman/swordwoman in history, fiction, real-life, or otherwise. Try to make a top 10 if you can.
"The Daemon lied with every breath. It could not help itself but to deceive and dismay, to riddle and ruin. The more we conversed, the closer I drew to one singularly ineluctable fact: I would gain no wisdom here."
Oh, I forgot to mention, it can include supernatural swordsman/swordwomen as well, such as Sephiroth, Ichigo Kurosaki, Link, and Even Sora, to even Harry Potter at the end of the second movie of the harry potter movies, whoever has held a sword in their hand and used it in combat counts, everyone, fictional superpowers, real-life people, Ezio, Altair, and any of the famous Assassin's would count here too, just name the best person to ever successfully wield a sword in history. They don't NEED to be important, just REALLY friggen AMAZINGGGGGGGGGG with a sword.
Redguard swordsmen from the Elder Scrolls were so skilled with their absurdly sharp blades that they could cut atoms in half and start nuclear explosions.
By swinging their swords with such precision that a nuclear explosion happens.
Also, I assumed this wasn't a versus thread. Because if it was, why not just give Superman a sword and proclaim him the best? Because Superman with a pocket knife is still far more powerful than anyone who has been mentioned in this thread.
Well, creating the explosion kills themselves as well.
And I wasn't meaning to make this into a vs. thread, but rather I was merely pointing out that knowing such a technique does not make them the greatest swordsmen. It does't mean they are incredibly fast, strong, or even extraordinarily skilled. Rather they just have very sharp blades. After all, I can't recall the technique ever being actually detailed so we can't say they were targeting a specific atom.