It could be a sword that can cut through any substance, like the Susanoo easily. Just imagine Naruto swinging it and slicing through powerful jutsu defenses as if they were paper.
It makes Naruto more powerful. He can defeat stronger enemies more easily.
Maybe it has the ability to absorb chakra. So when Naruto is in a fight against an opponent with a large amount of chakra, he can use the sword to drain some of that chakra, weakening the enemy while strengthening himself. The sword could then store that chakra for later use, like to boost Naruto's own attacks.
Well, in some fanfictions, Naruto might obtain the overpowered sword through a mysterious inheritance. Maybe it was left by a powerful ninja from the past and Naruto discovers it in a hidden cave or something.
It could be a super - charged kunai. Maybe it has some kind of special chakra - enhancing ability that makes Naruto's attacks much more powerful than normal.
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.
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.
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.
One common element is Naruto having new and extremely powerful jutsu. For example, he might have a super - strong fire - based jutsu that can destroy entire villages in one go. Another element could be that he has enhanced physical abilities like super speed and strength that make him almost invincible in combat. Also, he may have a special connection to some sort of ancient or powerful entity that gives him an edge over everyone else.
A common theme is rapid power growth. Since the focus is on Naruto being overpowered, he often gains strength much faster than in the original series. For example, he might quickly master difficult jutsu or obtain rare powers.