Not by someone else bro
It will be because his power was too strong for the blade
It will be because his power was too strong for the blade
2) The inverse actually has an example. Kaido's club is an ugraded weapon meaning some of the strongest characters could use less suitable weapons and be perfectly fine.
3) The sandai is still a famed blade and has withstood clashes with some of the strongest characters in the earth (kaido, Gandhi). if the only reason you want it to break is to upgrade to a higher grade weapon, that is in my opinion pointless. swords are as strong as the users are.
its more than likely the weapon You use is as strong as the haki of the user using it e.g vergo using a bamboo stick which should be quite brittle , as a weapon.