The Hammer of Thor in Norse fantasy novels is described in great detail. It is a large and imposing weapon. Its handle is made for Thor's grip, and the head of the hammer is solid and capable of delivering powerful blows. It is said to be enchanted, and when swung, it can create thunderous sounds and flashes of lightning. It is often shown as being indestructible, and its very sight strikes fear into the hearts of Thor's enemies. The hammer is also sometimes described as having runes inscribed on it, which may add to its magical properties.
Well, Thor's hammer could break when it faced extremely powerful enemies or was exposed to rare and powerful enchantments that it couldn't withstand. Sometimes, plot twists required such events to drive the story forward.
The story goes that Thor's hammer was crafted with great care and magic. It was bestowed upon him by Odin as a symbol of his strength and responsibility. The hammer's creation was a significant event in the mythological tale.
Fanfiction often takes creative liberties. It could be that there is a cross - over event that changes the nature of Thor's hammer's worthiness test. Maybe a powerful magical entity in the Harry Potter universe meddles with the hammer's magic. Harry Potter has shown great moral fiber throughout his adventures. His ability to love deeply, his sense of justice, and his unwavering determination against evil could be seen as the 'worthiness' factor by the hammer's magic, allowing him to lift it.
He could use the hammer as a tool in combat. Against his powerful foes in the Naruto universe, the hammer's unique abilities could give him an edge. For instance, he could use it to break through strong defenses that his normal jutsu couldn't penetrate. He might also use it symbolically, to inspire his friends and allies, just as Thor uses it in his own stories.