This is the relevent part of the code:
data "Boosts" "WeaponProperty(Magical);WeaponDamageDieOverride(1d8);WeaponAttackRollAbilityOverride(SpellCastingAbility);Attribute(InventoryBound)"

So all wpns do 1d8 and use spellcasting modifier for attack and dmg rolls. If the wpn is used in the offhand (without the fighting style) you dont get stat modifier in damage bonus.

BG3 Modder: https://www.nexusmods.com/baldursgate3/users/55895062?tab=user+files