As it stands there is no reason what so ever to use a sabre, typically of the 3-4 varieties available in game, the stats are no better than an average sword, or a bad sword.
In order for this weapon to actually have a specific usage, the slash damage probably should be massively increased, to the point where they’re the best slashing weapon in the game.
Historical basis for this is slashing weapons/sabres were typically used by infantry against foes who were lightly or not armoured. If plate armour receives a much needed buff against slash damage, this would work quite nicely with the existing stats set up for armour and weapons.
An added bonus to this would be Cumans, who typically have sabres, would be far more deadly in the early game and would then struggle to break through Henry’s armour once he get’s kitted out.