Does this artifact from Descent Into Avernus prove that magic weapons resize?

The accepted answer to Are there any guidelines in place governing the extent to which magic items can resize to different-sized users? only shows that “worn” magic items are supposed to resize to fit the wearer – not weapons.

I am interested whether the properties of the following artifact demonstrate that magic weapons also resize to fit the bearer.

Furthermore,

Given these two facts, must it be true that this artifact weapon can resize to best fit its wearer, whether Small/Medium or Large? And if so, does that mean that all magic weapons can do this?