Got it! However, since I have multiple weapons with different base attack and I don't want to have to create hidden counterparts for all of them (the hidden version of the weapon which overrides the base attack when equipped), I think I still prefer to change the editor setting, change the combatant's base attack and then change the editor setting back so it's ready when I want to instantiate another combatant. Anyway, when I create a combatant, my script overrides his base attack based on the equipment ability he has, so I don't really care about the default editor value for the base attack of my combatants.
Do you foresee any problem with this method?