The sword might be a gift from a mysterious magical being. This being saw potential in Harry Potter and decided to give him the sword as a tool to help him in his future battles. It could have been enchanted specifically for Harry to face the unique challenges he will encounter.
Perhaps the sword was created by the combined magic of the four Hogwarts founders. They foresaw a time when a great hero would need it, and Harry Potter is that hero in the fanfic. So it was made with their combined powers and knowledge, and it has special properties that only someone like Harry can unlock.
It could be an ancient heirloom from a long - lost wizarding family. Maybe it was passed down through generations and finally found its way to Harry.
In some fanfics, the sword is enchanted and has a mind of its own. The female Harry Potter has to form a bond with the sword, almost like it's a living being. This leads to some really interesting character development as she learns to communicate with the sword and use its powers to her advantage. She might have to face her own insecurities and fears as she does this. Also, the sword could be a symbol of a new era in the wizarding world, and her using it could spark a revolution or change in how magic is perceived and used.
One interesting plotline could be that the sword gives Harry Potter some special powers. For example, it might be able to cut through magical barriers that no other weapon can. This would make him more powerful in battles against dark wizards. Another plotline could be that the sword has a mind of its own and guides Harry Potter to hidden secrets or lost magical artifacts. It could lead him on a grand adventure where he discovers things about the wizarding world that were previously unknown.
One fanfic that might fit this is 'The Female Harry's Adventure with the Sword'. In it, the female Harry Potter discovers an ancient sword and uses it to face new and unique challenges in the wizarding world. It's a really interesting take on the character and the addition of the sword brings a fresh element to the story.
In some fanfictions, it could be a gift from a parallel magical dimension. There could be a race in this other dimension that is very advanced in combining magic and metalwork, and they see Harry as a hero worthy of such a gift. The metal arm could then hold the secrets and powers of that dimension, which Harry has to figure out how to use to save the wizarding world.
Basilisk blood could potentially be used for healing in fanfic, but with great risk. It's so potent that it might be able to cure otherwise incurable diseases or wounds in a wizarding world, but its dark and dangerous nature could also have unforeseen side effects, like corrupting the user's magic or mind. For example, a character desperate to save a loved one might use it, only to find themselves slowly losing control of their powers.
Yes, there are likely some out there. Fanfic writers often like to explore unique crossovers and alternative storylines. You can start by looking on popular fanfic websites like Archive of Our Own or Fanfiction.net. Just search for the keywords 'Harry Potter uses energy weapons' and see what pops up.
One possible storyline could be Albus getting sorted into a house that no one expected. This would lead to him having to prove himself in that house and deal with the initial doubts of his housemates. For example, if he was sorted into Slytherin, he'd have to show that he's not influenced by the old prejudices associated with the house.
One possible scenario is that Harry discovers the Force during his time at Hogwarts. Maybe there's a hidden chamber or an old artifact that unlocks this power within him. Another scenario could be that he meets a character from a different universe who teaches him about the Force. For example, a rogue Jedi who has somehow ended up in the wizarding world.
One possible magical property is that it can transform. It could turn into a different object when needed, such as a sword for combat or a shield for protection. It might also have the ability to store spells. Harry could load up the cane with spells in advance and then release them at a later time when he's in a difficult situation.