I'm kinda disappointed with this outcome, tbh. The original issue was "we won't allow you in even if you can make the sword disappear, because you'll still take it out during combat", which this is still the exact same scenario as. They would've had the same outcome as this if they'd walked away, vanished the sword like the original plan (instead of "vanishing" it into a ring), and then walked back through "without" the sword like they did this time.
I was kinda hoping Laplace would instead just make a more badass dress that could actually fit with the broadsword instead.
(edit: I guess to be clear, I know this was just an excuse for a yuri ring scene, but I think this being the justification for it feels kinda dumb even if the scene itself is cute)