He could start by training intensively with different weapons under the guidance of some old and experienced ninja. They might teach him the proper techniques and stances for using each weapon effectively.
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.
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.
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.
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.
It could be an old sage. There are often sages in the Naruto world who have access to powerful artifacts. An old sage might see Naruto's potential and give him the weapon to help him in his fight against evil.
Naruto might be a staff - type weapon. He could use it for both close - range combat and to channel his chakra or soul power. The staff could have different forms, like it could extend or transform into other shapes depending on the situation, similar to how he can transform his Rasengan.
In some fanfictions, Minato might use his advanced jutsu knowledge. He could teach Naruto some unique and powerful techniques that turn Naruto himself into a sort of living weapon. For example, Minato might enhance Naruto's Rasengan to a level where it can be used not just as an attack but as a strategic weapon that can change the course of battles.
In some Naruto fanfictions, her loyalty could be exploited. If a villain or a power - hungry group gets hold of Hinata and forces her to fight for them using her skills, she becomes a weapon against her will. Her skills, combined with her forced obedience, would turn her into a weapon in the hands of the wrong people in the context of the fanfiction.