I only ask this due to the rule of having to one hand your main weapon to have an offhand weapon that can be of any two hands (according to the question answered here. )
If the weapon stays in the main weapon slot, one could have a two handed set as their offhand, and a one handed main weapon as their main weapon.
In the case that the original standalone sword is pushed to offhand and the user can not one hand the main weapon, if such was the case what would happen to the off-hand weapon?