It might be a set of shuriken, but not the ordinary ones. These shuriken could be larger and have a unique shape, like the outline of a wave. They could also be made of a special metal that's resistant to most forms of damage and has the ability to return to Naruto's hand like a boomerang.
Well, it could be a key to unlocking new powers for Naruto. Maybe it has some special chakra - enhancing properties that help him in battles against stronger foes.
The shadow weapon might be an ancient relic from Wave. Maybe it was created by a powerful shinobi from Wave long ago and has been lost until Naruto found it.
It could also change his stealth abilities. Since it's a shadow weapon, it may allow Naruto to blend into shadows more easily, making it easier for him to spy on enemies or launch surprise attacks. This would be a great advantage in his ninja missions.
In some Wave - related fanfictions, Naruto might find a unique sword. It could be a sword with special powers like being able to cut through almost anything. Maybe it has some sort of chakra - enhancing property.
Perhaps it's a unique staff. A staff could have different uses, like being a conduit for chakra. It could also have hidden compartments or be made from a rare material that gives Naruto an edge in battles. For example, it might be made from a metal that can absorb chakra attacks and then redirect them.
Well, it could be a sword with the power to cut through any jutsu. Maybe it has some special markings that only Naruto can understand. It might also be a staff that can control the elements in a unique way, giving Naruto an edge in battles.
Yes, sometimes he finds a rare dagger. This dagger might have a special symbol on it that gives it a connection to an ancient clan in the Wave region. It could hold secrets or powers related to that clan.
If the weapon is a chakra - enhancing tool, it will boost Naruto's existing jutsu. For example, his Rasengan could become more powerful, being able to break through stronger defenses.
In some fanfictions, when Naruto finds a cave in Wave, he might discover a hidden treasure. This could be a special weapon or some ancient scrolls that hold powerful jutsu. It could also be a place where a hermit or a powerful being once lived, and Naruto may find clues about a long - lost technique or a way to defeat a great enemy.
His friends might be a bit wary of the sentient weapon at first. Sasuke, for instance, might be suspicious and think it could be a danger. But Naruto would try to convince them that it's okay. Over time, if the weapon proves useful, they could come to accept it.