I think a chakra - infused sword would be great for Naruto. This type of sword could be used to channel his own chakra, allowing him to perform unique attacks. It could also change shape or size depending on the amount of chakra he pumps into it. For example, it could extend to reach far - away enemies or become wider for more powerful slashes.
A sword with a unique ability, like the ability to absorb chakra, would be a good fit for Naruto. This way, he could use it to nullify an opponent's chakra - based attacks. It could also be a sword that has a connection to his Nine - Tails chakra. Maybe it glows red when he taps into that power, and it becomes even more powerful, allowing him to cut through almost anything.
A katana with a lightweight blade would be good for Naruto. Since he is used to quick movements and acrobatics, a heavy katana would slow him down. Maybe one with a blue - tinted blade to match his ninja - wear colors. It could also have some chakra - conductive properties to enhance his attacks.
Naruto would need training in swordsmanship fundamentals. This includes proper grip, stance, and basic slashing and thrusting techniques. He would also need to train his balance, as using a sword requires different body movements compared to his normal fighting style.
Maybe a zanpakuto with the power to heal. Naruto is all about protecting his friends and village. So a zanpakuto that can heal wounds during battle would be very useful. It could also have a secondary ability to boost the chakra of his allies. This would fit with Naruto's selfless nature.
He could wear long, flowing robes. The length would complement his tall stature, and the flowing fabric would add a sense of grandeur. Maybe something in a dark color like black or deep blue to give him an imposing look.
The sword - Naruto might have the ability to channel his chakra. So it could be used to perform powerful attacks like chakra - infused slashes. Just like how Naruto can use his Rasengan in his normal form, the sword could release a similar type of energy attack when swung with enough force.
The sword could have the ability to cut through any chakra - based attacks. Since Naruto's world is full of ninjas using chakra, this would be a very useful ability. It would allow Naruto to easily defend against and counter his opponents' attacks.
Well, in some fanfictions, he might inherit it from an unknown ninja clan. Maybe his parents left it for him and it was hidden until he discovers his true heritage.
In a fanfic, Naruto may make a sword that is connected to his Nine - Tails chakra. The sword could have markings on it that glow red when he taps into the Nine - Tails' power. It would be extremely powerful, capable of cutting through almost anything, and also have the added benefit of intimidating his enemies.
It could be a chakra - infused sword. This type of sword can enhance the user's chakra attacks when swung.
The demon sword could potentially give Naruto new jutsu. Maybe it has some sort of dark energy that he can learn to manipulate and turn into unique attacks. However, he would have to be careful not to let the dark side of the sword overtake him. He might start with simple things like using the sword to focus his chakra in a different way, creating new types of rasengan-like attacks.