He could become a weapons master through some kind of special power-up. For example, a new chakra form that gives him an affinity for weapons. He might be able to infuse his chakra into weapons, making them more powerful. And Naruto is known for his hard work, so he'd surely spend countless hours training with various weapons, from swords to shurikens, until he masters them.
The katana would be really interesting. A katana in Naruto's hands could be a powerful weapon. He could use his speed and strength to make swift and deadly strikes. Also, a chained weapon like a kusarigama. He could swing it around with great force and use his ninja skills to control its movement in battles, entangling his enemies.
In this fanfiction, Naruto could master shurikens in a new way. Instead of just throwing them, he could learn to control their flight path precisely with his chakra. Another weapon he might master is the naginata. It's a long - handled weapon that he could use to keep enemies at a distance while also delivering powerful blows.
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.
Another weapon he might master could be a chakra - enhanced sword. He could learn to change the shape and properties of the sword's blade using his chakra. For instance, he could make it superheated to cut through extremely tough materials or elongate it to reach enemies at a distance. This would give him an edge in close - combat situations against opponents with strong defenses.
In some fanfictions, Naruto might become a genjutsu master by training intensively with a reclusive genjutsu expert. This expert could teach him unique and ancient genjutsu techniques that are not commonly known in the ninja world.
In this fanfiction, Naruto might also create a shield. This shield could be made from a combination of rare materials he discovers during his adventures. It has the ability to not only block physical attacks but also absorb and redirect chakra - based attacks back at the enemy.
One way is to base the weapons on existing ninja tools in the Naruto universe. For example, you could create a modified version of the kunai, like a kunai with a hidden blade that can extend for surprise attacks. Another idea is to draw inspiration from nature. Maybe a weapon made from a special tree in the Hidden Leaf Village that has unique properties, such as being able to absorb chakra.
In Naruto weapon master fanfiction, one of the most creative weapons could be a sword that can change its shape according to the user's chakra nature. For example, if the user has a fire - based chakra, the sword might transform into a blade engulfed in flames, adding more power to their attacks.
In some fanfictions, Naruto becomes a shadow clone master through intense and unique training regimens. For example, he might train with a hermit who teaches him secret methods of chakra control specific to shadow clones.
Some fanfictions describe that Naruto chakra weapons are created by skilled blacksmiths who have a basic understanding of chakra. They infuse chakra - conductive materials with the user's chakra during the forging process.