Swap to your back bar (which has 2h) and then back to front bar. You'll notice there is a swap animation when you go from dual wield to 2h. But when switching back to dual wield, the 2h just vanishes and daggers teleport to your hands.

Now, swap to back bar where you have the 2h weapon. Then sheathe your weapons. Make sure you have some personality selected. Press bar swap. Notice that instead of your toon making the swap animation and unsheathing the dual wield, the daggers just teleport to your belt and your character has no personality any more. Start jogging and now the personality is there but without any accessories the personality might have. Stop and the standing (idle) is again without any personality.

I wanted to add that I observe also wrong stances on dual wield weapons on front bar when I have a destro on the backbar. The dual wield wepaons are then held like I had a destro staff in my hands.

Overall it looks like when switching back from backbar to front bar the frontbar drawn weapon stance is not loaded at all until I stow back my weapons. At least if frontbar is dual wield. I did not test in on other weapons on frontbar.