Well, in the fanfiction, the rare sword might have some sort of special power. It could be linked to an ancient ninja clan. Naruto might have to go on a quest to discover the true nature of the sword and how to fully utilize it. This could lead to him making new allies or enemies along the way.
The sword could potentially change Naruto's fighting style completely. Since he's mainly known for his shadow clones and Rasengan, the addition of a sword could add a whole new dimension to his combat. He might start training with Kakashi or some other sword - expert ninja to master the use of this rare weapon. And who knows, this sword could also have a connection to the tailed beasts, like it was used in the past to seal or control them in some way.
The dragon sword could be a key to unlocking an ancient prophecy in the Naruto universe. Naruto, with the sword in his possession, might be seen as the chosen one to fulfill this prophecy. It could involve bringing peace to a long - warring region or uniting different ninja clans. He would have to go on a journey to understand the true meaning of the sword and his role in the prophecy, facing many trials and making new allies along the way.
The Raijin Sword could also have some sort of connection to Naruto's chakra or his Nine - Tails power. It could potentially unlock new forms or power - ups for him. For example, the sword's energy could combine with the Nine - Tails' chakra, creating a unique and extremely powerful attack.
It could be a chakra - infused sword. This type of sword can enhance the user's chakra attacks when swung.
Well, he might gain access to super powerful summons that no one has ever seen before. These could give him an edge in battles, like against the Akatsuki.
Naruto getting kidnapped by Orochimaru would be a really dangerous situation. Orochimaru could start by putting Naruto in some sort of chakra - suppressing device. This would limit Naruto's ability to use his Nine - Tails power. Then, he might try to implant some of his cursed seals on Naruto, which would give him more control over Naruto. But Naruto has his own allies within himself. The Nine - Tails, despite their rocky relationship, might help Naruto out in this situation. Also, Naruto has the memories of all the people who care about him. He'd draw strength from those memories and keep his hope alive, waiting for the moment when he can break free and return to his friends and the village.
In this kind of fanfiction, Naruto might become very distrustful. He could isolate himself from his friends for a while as he tries to deal with the pain of being cheated on. Maybe he would focus all his energy on training to forget about the heartbreak.
Well, he could become a much more powerful ninja. The demon knife might have special abilities like being able to cut through any defense or it could give Naruto the power to sense his enemies from afar. He would need to learn how to control the power of the demon knife though, as it might be too much for him at first.
Well, he could gain some amazing new abilities. The Sharingan is known for its copying abilities, so Naruto might be able to copy jutsus more easily. He could also potentially gain some of the Uchiha clan's unique powers related to genjutsu. This would change his combat style significantly, making him even more unpredictable to his enemies.
He might start training with it. Naruto is always eager to improve his skills, and a new sword could be a great addition to his combat abilities.
Well, Naruto could have a powerful new ally. The sentient sword might be able to communicate with Naruto, giving him advice in battles. It could also have special abilities like being able to cut through any material, which would be a great advantage for Naruto.