As it stands, if you are dual wielding and you want to change primary, if the offhand is too heavy, the game won't let you, and nothing happens.

Instead, it should be that you now have the weapon you want in primary and the too-heavy weapon in your offhand should be auto-removed, so now you wield your weapon of choice in primary, and empty hand in offhand.

Happy holidays!

We couldn't come to any consensus or preference on how it should work.

So instead just change your associated wield if you want to change your other wield.