As time continued to pass there was some weapon owner that would point out that the weapons lack free will of their own. They were not mindless but at the same time, they were not actually choosing their owners at all. It seemed they were being played and it was through one thing that was being used to play them more than anything else
Worthiness.
That was something that did play a key factor however it had nothing to do with the will of the weapon at all. It all had to do with a person matching both their magic and innate skill with the weapon that each of the otherworlders had become. Just matching their magic with the weapon was not enough as they had the certain innate skill to use the weapon as well. This natural affinity to both their magic and their weapon form is what causes them to force the weapon to obey them and break through the shell their bodies had become.