As far back as I can remember, in Mout & Blade, traditionally, the effectiveness of a duel is decided by athletics in first, and not by the weapon or his character's melee skill. And, of course, I will not say anything new: the heavier the character, the longer the weapon he needs for a comfortable 1 vs 1 duel in an open area.
The one-handed sword has always been and remains a versatile weapon against any other melee weapon.
Keep in mind that if you go up against a light infantryman with a two-handed sword 1 vs 1, he will simply win the duel, keeping his distance, if he is not a noob.
I tested standard one-handed swords in a duel against two-handed swords with equal armor weight and unit class - everything is balanced no worse than a Warband. Also I noticed that the classes in Bannerlord differ significantly from each other than in Warband. For example, a Kusaite archer with heavy armor and a short saber has almost no chance against an infantryman with a two-handed sword.