After seeing people (incorrectly) compare Byleth to the Monster Hunter, I have decided to list off every weapon class in the game so that we are all aware that they won't play like Byleth all that much.
Greatsword-Big, slow, clunky, and strong as ****. It'd be like Ganondorf's D O R I Y A H on steroids more than anything.
Long Sword-Basically a big katana. Favors an iaijutsu-like style that isn't represented in Smash yet.
Sword and Shield-Exactly what it says. Would probably be the closest to Link's fighting style, but a bit swifter and more refined.
Dual Blades-A swift, multi-hit style. The closest match would be the Pits, but would be a lot more direct and less heavy on the twirling.
Hammer-Abandons defense for ludicrous damage output. Would be a lot faster and more wild than Dedede or the Ice Climbers, and wouldn't work like Amyr.
Hunting Horn-A weird, buff-giving weapon. Plays somewhat like a much weaker hammer to act as a supporting fighter.
Lance-A long-range weapon with a heavy shield. It's like stabbing a potato with a toothpick; You have pathetic damage output and the monster has no damage output. It would lack Areadbar's sweetspot and be a lot tankier, too; In other words, it plays nothing alike.
Gunlance-A long-range weapon with cutting damage and the ability to fire off explosive rounds. It would be geared towards mid-range combat and wouldn't work like Areadbar, either.
(Nintendo) Switch Axe-A weapon that can switch between sword and axe, and can gain helpful properties. It could work somewhat like Amyr, but I think it would be a fair bit faster and more aggressive.
Charge Blade-A different take on the Switch Axe, being used for storing up power and delivering explosive bursts. Again, it could work like Amyr, but would probably be a bit faster.
Insect Glaive-A unique weapon that gives you mastery in the air. Much faster and more air-focused than Areadbar, and would probably take up the bulk of the aerial moves.
Bowgun-Long-range weapons that come in Light and Heavy variants. Has a lot of different bullets and shot types, most likely to be used differently than most Smash firearms.
Bow-The closest match to any Smash weapon. Would probably be used similarly to Failnaught, but with some extra utility.