A lot of people don't know this, but gigantic creatures but gigantic muscular creatures are very hard to cut through. Like I saw the Anaconda horror movie, and the woman cut off the giant snake's head with a machete. But then I heard in real life a boy was attacked by an anaconda, and they fought it for almost a half an hour with a machete, unable to kill it until somebody arrived with a shotgun.
And then I think about fantasy swords and wonder why you even need a super sword when a regular one will do against most opponents, especially unarmored ones.
Well, you, miss, have answered all the questions! How do you cut giant muscle monsters easily? With a super sword! Why do you need a super magic sword? To cut through monsters like it's a hot knife going through butter!!!!