It might also be related to some sort of experiment or exposure to a unique chakra - based substance. Maybe he was exposed to a mysterious ice - chakra crystal during a mission, and over time, his body adapted to it and he gained the ability to control ice.
It could be a result of some kind of rare genetic mutation. Maybe there was a dormant gene in his Uzumaki bloodline that got activated under certain circumstances, like during a near - death experience or a powerful chakra surge.
Well, in some fanfictions, Naruto's water - controlling ability could be a gift from a powerful sage. This sage, seeing Naruto's potential and his need for new powers to face upcoming threats, bestows upon him the ability to control water. Another origin could be that Naruto accidentally absorbs the chakra of a water - using enemy during a battle, and this chakra somehow melds with his own, giving him the power to control water.
It could also be a result of a powerful curse or blessing. For instance, he might be cursed by an old enemy with the ability to control time as a side - effect, but he then learns to master it. Or, it could be a blessing from a sage or some other powerful being who sees Naruto's potential and gives him this unique ability to help him save the world.
In some fanfictions, it could be due to a genetic mutation or an unexpected side - effect of a jutsu he uses. For example, if he experiments with a new form of chakra manipulation, it might accidentally give him the power to summon swords. Or maybe it's a gift from the Sage of Six Paths in a different interpretation of the Naruto universe.
One possibility is that it could be related to some ancient bloodline limit that was dormant in Naruto all along and somehow got activated. Another could be that he received some sort of special training or exposure to a unique chakra source that granted him this power.
It could be from some sort of ancient ninja training that was lost and he somehow discovers it. Maybe there's a hidden scroll or a hermit who teaches him this fire - controlling ability.
One possible origin could be some kind of ancient bloodline. Maybe Naruto has a hidden bloodline that was passed down through generations and finally awakened, allowing him to summon angels. Another option is that he got this ability through a special training or a quest. He might have found a hidden place or an old sage who taught him the art of summoning angels.
One possibility is that he inherits it through some sort of bloodline connection that was previously unknown. Maybe there's a distant relative who had the ability to control sand, and it somehow got passed down to Naruto.
One possibility could be some sort of new training he undergoes. Maybe he discovers a hidden jutsu scroll that teaches him how to control and produce fire from within his body. This could be a long - lost technique from an ancient ninja clan.
He could develop an ice - dragon technique. He would summon an ice - dragon made of his chakra that can fly around and attack enemies with its ice - cold breath or sharp claws. Another could be the ice - prison technique, where he traps his enemies in a large ice cube.
Well, it could enhance his combat skills significantly. He could use ice to create barriers for defense, like forming thick ice walls to block enemy attacks. Also, he could make ice weapons such as ice shurikens or ice swords to attack from a distance or in close - quarters combat.