Naruto and Sasuke have always been portrayed as rivals since the beginning of the story. Both characters ended their conflict with a serious battle for the second time in the Valley of the End.
This time, both were significantly weakened; Naruto had utilized the full power of the Sage of Six Paths, while Sasuke had attained the Rinnegan. In this climactic battle, Naruto emerged victorious, but the cost was quite high. Both Naruto and Sasuke lost an arm.

Naruto and Sasuke are left without an arm after the final battle
The fact that Naruto and Sasuke lost an arm has shocked many fans. However, for the creator Kishimoto, this decision was very significant. In reality, he had been planning this for a long time before the story reached the final battle.
According to Kishimoto, he wanted Naruto and Sasuke to have a battle that did not rely heavily on techniques. The reason behind this decision was simple: he wanted it to be a heartfelt duel between two characters who deeply understand each other’s feelings through their past encounters.
As the author stated, this battle needed to be resolved with a more profound emotional impact rather than by any other means, and in fact, he received quite a bit of criticism from his peers regarding this point.
Kishimoto also mentioned that he decided to have both Naruto and Sasuke lose their dominant arms in this battle. As fans know, Naruto lost his right arm while Sasuke lost his left. Both performed their ultimate techniques at the end of the battle using their dominant arms, leading to their loss.
The mangaka explained that this was done with the intention of symbolizing a shared burden between the two characters. After the battle, instead of simply showing a peace offering, Kishimoto intended to create a deeper emotional connection by having them literally lose their arms. Unlike previous instances where a handshake symbolized reconciliation after a battle, this time, Kishimoto chose to portray their loss of arms as a reason for not shaking hands.
Yet, Kishimoto cleverly utilized the symbols of Hashirama and Madara in the aftermath to create a new metaphorical gesture. This worked well because both Hashirama and Madara represented Indra and Asura, similar to Naruto and Sasuke.
This symbolic gesture not only created a metaphorical bond for Naruto and Sasuke but also for Madara and Hashirama, representing Indra and Asura, who have battled through many lifetimes.
This is a distinctive hallmark of Kishimoto, an author who had intended for this moment to be significant from the first part of the story. The first part unfolded quite a while ago, indicating that Kishimoto had indeed planned for both Naruto and Sasuke to lose an arm from the very beginning.

Of course, in the end, Naruto received a prosthetic arm created from Hashirama’s cells, while Sasuke continued to live with his arm missing, likely due to the ongoing journey of atonement he started at the end of Naruto. Even today, Sasuke still feels a deep remorse for his past actions. It’s evident that years after this battle, Sasuke still considers himself a shinobi striving for redemption.