Well, it could be really interesting. Maybe Naruto discovers Hinata in a strange situation where she's been cursed or something and she gradually transforms into a sword. Naruto then has to figure out how to reverse it while also using the sword - Hinata in battles against powerful enemies.
I'm not sure if there is such a specific fanfiction. Fanfiction is a vast world with all kinds of creative ideas, but this one seems rather unique. It might be a very niche or even a new and unheard - of concept in the fan - created Naruto stories.
The sword - Naruto might have the ability to channel his chakra. So it could be used to perform powerful attacks like chakra - infused slashes. Just like how Naruto can use his Rasengan in his normal form, the sword could release a similar type of energy attack when swung with enough force.
It could be due to a magical artifact. Suppose Naruto comes across an ancient and mysterious sword - like artifact. When he touches it or tries to use it, it backfires and instead of him controlling the sword, he is transformed into it. This could lead to a whole new adventure as his friends try to figure out how to reverse the transformation.
I have a few novels that I can recommend to you. They are all stories about beautiful women turning into sword immortals. The first was " It's Not Easy to Be a Sword Spirit ", which told the story of the female protagonist, Xia Xin, who was taken in as a sword spirit by the God of War after experiencing 30,000 years of punishment. She regained her memories, pacified the chaotic world, lost her beloved, and traced back to her previous life. This novel had elements such as two male leads, amnesia, and three lifetimes. In addition, there was the story of the Supreme Demon. The main character, Lin Hui, found a broken sword and traveled to another world. He discovered that the broken sword contained four beautiful sword spirits. These novels could be read online.
In some Naruto fanfictions, Hinata could potentially be portrayed as a 'weapon' in a very metaphorical sense. For example, her Byakugan abilities might be exploited in unique ways that make her seem like a strategic weapon for a side or a cause. But in the canon Naruto story, she is a character with her own agency and not really a weapon.
One great source for Naruto and Hinata fanfiction could be FanFiction.net. You can search for stories specifically focused on their relationship there. There are often new and interesting takes on their story, from how they first fell in love to their married life in the future.
Perhaps in the fanfiction, Hinata wears a micro bikini for a special festival in the Hidden Leaf Village. Naruto is really excited to see her in it. They participate in the festival games together and Hinata's new look makes Naruto see her in a different light, more as a strong and confident woman.
One possible fanfiction could involve Naruto learning kenjutsu skills and Hinata being inspired by his newfound abilities. Maybe Naruto discovers an ancient sword technique and Hinata supports him in his training, leading to a deeper bond between them.