The last epic, intense 1v1 duel with swords that I remember was Nidhogg. I was sitting on a mate's couch, and we were just going back and forth, back and forth. He'd capture one screen, get all the way to the end — and then I'd claw my way back.
It was way too intense for what was supposed to be a light-hearted night of drinks and games. But it was great. And it's the same thing that watching duels in For Honor reminds me of.
PC Gamer has posted up a slice of footage from PAX West featuring 1v1 duels with the Kensei, Warden and Raider. It's always a tight tussle. Fights are a best of five affair, with individual rounds lasting a maximum of five minutes each. (Although they often go for about two or three minutes.)
It's starting to make For Honor's appeal much, much clearer to me: almost like a big budget Chivalry: Medieval Warfar, with a 1v1 duel mode for friends and bigger modes for when you want those larger scale fights.
But man, I don't know. The duel mode is looking really good. I hope there's some form of LAN play or local play. The biggest flaw with these kinds of games is when you're struck with lag and you can't defend as quickly as you need to.