Well, he might first be really confused. He never knew his mother well, so finding her sword would be a huge shock. He could start having dreams or visions related to his mother when he touches the sword.
The sword could lead Naruto to new training. Maybe it has a special technique that only those related to his mother can learn. So he has to figure out how to unlock that power. And this new power could help him in his battles against stronger enemies in the future. Also, it could make his relationship with Sasuke more complex as Sasuke might be curious or even jealous of this new discovery of Naruto's.
If Naruto finds his mother's sword in a fanfiction, it might lead him on a journey of self - discovery. The sword could be a symbol of his heritage. It could also attract the attention of enemies who either feared his mother or want the power of the sword for themselves. This would then put Naruto in a dangerous yet exciting situation where he has to protect the sword and learn about its significance.
In a 'Naruto Finds a Legendary Sword' fanfiction, a lot can happen. The sword might have a connection to Naruto's family. It could be a heirloom that was lost generations ago. This discovery could lead to Naruto learning more about his family's past and his own heritage. He may also have to go on a quest to fully understand the sword's powers and how to use them. He might meet new allies along the way who help him in his journey. There could be epic battles against those who want to steal the sword from him, and Naruto would have to use his wits and newfound sword skills to defend it.
He might start training with it. Naruto is always eager to improve his skills, and a new sword could be a great addition to his combat abilities.
He could find the sword in an ancient tomb. This tomb might be filled with traps and puzzles that Naruto has to overcome. Once he gets the sword, he discovers that it glows when near an enemy's weak point. So, he starts using this ability to his advantage in battles.
The sentient sword could also have a tragic past. Maybe it was once used for evil and now wants to atone by helping Naruto. It could share its knowledge of ancient jutsu or forgotten battles with Naruto, which would give Naruto an edge in his future fights.
Well, he might discover that the sword has some special powers. Maybe it can cut through any material, or it could have the ability to absorb chakra. He could start training with it to become even stronger in battle.
He could use it to discover more about his Uzumaki heritage. Maybe the sword has some special powers or markings that are related to the Uzumaki clan. It could also put him in danger as others might be after the sword for its power or value.
In such a fanfiction, Naruto might take on a protective role. He could use his ninja skills to keep the toddler safe from any potential threats in the Naruto world, like rogue ninjas or dangerous beasts.
Well, it could be that the sword is significant in terms of Naruto's growth. Since it was his mother's, it might hold memories or chakra imprints that help Naruto in his battles. It could also be a key to unlocking some sort of family heritage within him. For example, it might allow him to access a special form or ability that only his mother's side of the family had. This would give him an edge in combat and also help him understand more about his family background.
In such a fanfiction, Naruto might have an emotional moment. He could finally learn more about his family's past directly from his mother. Maybe she would share some secret jutsu or wisdom with him.