Naruto could have the power of solar - powered regeneration. The sun is often associated with life and renewal. So, if he gets injured, his wounds could heal faster with the energy of the sun. He may also be able to use the sun's energy to enhance his physical strength. He could run faster, jump higher, and hit harder as if he was charged up by the sun's power.
He could gain the ability to freeze Grimm. In RWBY, silver eyes have the power to harm and sometimes even stop Grimm in their tracks. Naruto's already impressive combat skills combined with this would make him a formidable force. He might also gain enhanced vision, like being able to see in the dark better or detect hidden threats more easily.
He could probably gain the ability to phase through objects. Just like wraiths are often depicted as being able to pass through solid things. This would give him an edge in combat and also in sneaking around.
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 might gain the ability to cut through any chakra - based defenses. Since the Master Sword is often depicted as a very powerful weapon, it could enhance Naruto's combat capabilities against tough opponents.
Naruto could gain some really cool and unique abilities. For instance, he might be able to transform his body into different forms, like a phoenix made of chakra and magic energy. His speed could be enhanced to a superhuman level, not just by chakra - enhanced movement but also with the magic in his bloodline adding an extra boost. He could also develop the ability to create illusions that are not just based on chakra, but also on the magic within him. These illusions could be so powerful that they can deceive even the most experienced ninjas.
One new ability could be Force jump. Naruto could use the Force to propel himself into the air much higher and farther than his normal jumps. Another would be Force sense, which would let him detect hidden enemies or traps more easily. He could also use the Force to influence the minds of his opponents on a minor level, like creating distractions or making them hesitate during a fight.
He might gain enhanced speed and strength. The fox is known for its agility and power, so when summoned, it could transfer some of those traits to Naruto. For example, he could run faster than he already can and deliver more powerful punches.
He could gain the ability to absorb chakra on a much larger scale. With his greedy nature, he might use this to hoard chakra from others, making himself super - powerful. He could also gain the power to control the six paths, which he might use to dominate others rather than for the common good.
Naruto might be able to create cloud - based illusions. Just as he can create shadow clones, with the power of Cloud sealed in him, he could project illusions made of clouds to deceive his opponents. These illusions could be large - scale and very realistic, confusing enemies about his true location and intentions.
One new ability could be enhanced perception. Characters with Haki could sense the presence of hidden enemies during the Chunin Exams. For example, Sasuke could use Haki to detect any assassins sent by Orochimaru that are lurking in the shadows. Another ability would be the power to intimidate opponents. Just like how Luffy uses his Conqueror's Haki in One Piece, in the Naruto fanfiction, a character like Gaara could use Haki to make his opponents tremble in fear, giving him an edge in battles without even having to make a move.