One of the benefits of communicating with soul weapons was that, rather than using words, they spoke with thoughts and emotions. As such, even if Michael and his weapons were to engage in a deep philosophical debate, it would last barely a few seconds in real time.
Perhaps the biggest boon of them was that with the addition of Heaven's Judgment, Michael and Devil wouldn't get blinded as easily, making it much easier to predict the enemy's patterns and plans at a moment's notice thanks to the extra point of view.
Deciding to let them rest, Michael made both weapons enter his soul, though not before instructing them to behave.
He had a lingering feeling that if left to their own devices, these two could argue until the end of time, only to never agree on a single thing.
