idk if this is ever answered in canon bc its been so long since ive watched soul eater, but what happens when two weapons are a team and switch using the other to keep up their strength during battles? why dont all weapons have a weapon Meister and become a weapon army to take over the world?
you see a little of that with the thompsons but i think that they’re a special case as they are siblings they’re naturally inclined towards being on the same wavelength
my theory is that in most cases weapons can’t match wavelengths - one weapon trying to wield another will result in what happened when black☆star tried to wield soul - they didn’t match up, so he couldn’t even lift the weapon. it’s only weapons who are incredibly in sync like liz and patty who can wield each other, and maka and soul in the anime.