In some fanfictions, the Buster Sword could be enchanted. So Naruto might gain abilities like being able to send out energy slashes from the sword. These slashes could travel long distances and be very powerful, capable of taking out multiple enemies at once. Also, it could have a special connection to Naruto's chakra, allowing him to channel his chakra into the sword more effectively and use it in new and creative ways during combat.
Perhaps the Buster Sword could give Naruto the ability to fly or levitate for short periods. This would add a new dimension to his combat skills as he could quickly move around the battlefield in the air, making it difficult for his enemies to predict his attacks. And it could also have some sort of defensive ability, like creating a shield of energy around Naruto when he holds it in a certain way, protecting him from incoming attacks.
It could have the power to cut through almost anything. Since Naruto is a powerful ninja, the sword might inherit some of his chakra's strength, allowing it to slice through thick barriers or even powerful jutsu defenses.
Naruto could potentially gain the ability to sense danger more acutely with Akame's sword. In some interpretations, the sword has a certain awareness. This could help Naruto in battles, allowing him to anticipate his opponents' moves better. Also, if the sword has any hidden powers related to Akame's world, Naruto might be able to tap into them. For instance, if there are special enchantments on the sword, he could use them to his advantage, like making himself invisible or resistant to certain types of attacks.
He might infuse the sword with his chakra. Since Naruto has a large amount of chakra, he could make the Buster Sword glow with his unique chakra color. This would not only make the sword stronger but also give it new abilities. For instance, the chakra - infused sword could cut through stronger defenses or even repel enemy ninjutsu.
Naruto might gain the power of shikai and bankai. Shikai is the first release of a zanpakuto's power, and bankai is the ultimate form. Naruto, with his determination and strong will, would strive to master these forms. Shikai could give him new attacks and defenses, while bankai could make him an extremely powerful force. For example, his bankai could combine his ninjutsu skills with the zanpakuto's power in a unique and devastating way.
Naruto could gain the ability to manipulate light and darkness, which are often associated with Keyblades. This would be a huge change from his normal chakra - based abilities. He could also use the Keyblade to fly, giving him an advantage in both mobility and combat. Another new ability might be the power to heal, as some Keyblades have restorative properties.
The sword could give Naruto an advantage in close - quarter combat. Since Naruto is mainly known for his long - range attacks and his ability to transform into the Nine - Tails, having Zabuza's sword would force him to improve his close - combat skills. This could lead to him developing new evasion and counter - attack maneuvers, making him a more well - rounded fighter in the fanfiction.
He could gain the ability to predict his opponents' moves more accurately. The Sharingan is famous for that. So Naruto would be even better at dodging attacks in combat.
He could gain the ability to create large - scale wooden structures, like Hashirama did. For instance, he could build huge wooden golems to fight for him in battles.
Naruto could potentially gain the power of omnipotence. Since the Infinity Stones are extremely powerful in the Marvel universe, in the Naruto fanfiction, they could give Naruto abilities beyond imagination. He might be able to use the Stones together to rewrite the rules of the ninja world. For example, he could make chakra obsolete and introduce a new form of energy using the combined powers of the Stones. Also, he could use the Power Stone to boost the power of his Rasengan to an unimaginable level, capable of destroying entire mountains with a single throw.
He might gain enhanced chakra control. Since he has the Kyuubi's soul, he could have better access to the Kyuubi's chakra reserves and be able to manipulate it more precisely. Maybe he could also gain some of the Kyuubi's natural abilities like better senses, especially smell, which could help him in tracking enemies or finding things.