There are several times throughout Boruto where Sasuke could have taken advantage of the spare arm, although he didn’t always need it.
One of the key elements with Sasuke entering Boruto is the fact that he only has one arm. It was a choice he made as growing it again with Hashirama cells would take months. Since he was about to embark on a journey of redemption and discovery, he didn’t want to waste time.
It gives the character an interesting new wrinkle as he has had to adjust the way he fights due to the loss of the appendix. For the most part, he’s handled it very well, but there have been times when he certainly wishes he had it back.
10 Spare arm needed: hinders your Kenjutsu and Taijutsu
For the most part, Sasuke only used one hand with whatever sword he used, giving him a burst of speed with them, but that doesn’t change that the lack of a second hindered him. It is especially true in a taijutsu fight where the blows come to you so quickly that you have little time to think. Having an inability to defend an entire side of your body presents a major weakness, and one that Sasuke has continually had to reckon with.
9 Thrived Without: Helped Focus His Mind During His Redemption Journey
After the war ended, Sasuke embarked on a journey of redemption. He was at a loss seeing how the world looked from his new perspective, to make up for his past actions. While the loss of his arm didn’t have a direct effect on that, it served as a constant reminder of what he once was. In many ways it was an act of penance, as he could very easily have gotten a new one if he wanted to. It helps you keep you attached to who you once were as you go through life.
8 Replacement arm needed – his battle with Kinshiki would have turned out differently
Even without the arm, the battle with Kinshiki was an incredible sprint of kenjutsu action. The two clashed immediately, wasting no time to speak.
As long as Sasuke stood his ground, there is little doubt that he would have been better off with two hands on his sword hilt rather than one. The extra pressure could have helped with the thudding Kinshiki was landing with his chakra blades. He could have thrown more an attack instead of being constantly on the defensive.
7 Thrived Without: Improved your hand’s sealing speed
It would be understandable if Sasuke’s ninjutsu skills were reduced due to the loss of his arm, as hand seals tended to require two hands to function effectively. Sasuke managed to overcome this deficiency admirably, as he is now able to not only complete them with one hand, but to do so at speeds that only Madara was capable of. It’s a feat that shows just how powerful a ninja Sasuke is and how resourceful he has always been.
6 Replacement Arm Needed – To help compensate for how often you have to use your Rinnegan
The downside of the fact that almost every villain in Boruto is linked to the Otsutsuki is that it forces Sasuke to use his Rinnegan in a ridiculous amount. In almost every fight, Sasuke has to translate himself and others into one of their dimensions, as he is the only one who can. It undermines how refined a fighter has become and has been used to weaken him in fights. Sasuke is running out of chakra because his dojutsu is practically a meme at this point.
5 He thrived without: helped him become an intellectual fighter again
Throughout most of the series, Sasuke was shown to be an intellectual fighter who always used his brain in battle. That started to change after he defeated Itachi. Instead, he began to rely on the powers of his Sharingan and threw caution to the wind in many cases.
His battle against Killer B and his skirmish with the Kage are examples of that. The loss of his arm has given him a weakness that he has had to fix, allowing him to show his strategic genius again.
4 Replacement Arm Needed: To be a better teacher for Sarada and Boruto
Teaching and Sasuke don’t go very well together, as he freely admits that he’s not the best at conveying things verbally like Kakashi is. He’s more of a knee-jerk learner and a fighter, making it difficult for him to explain things. While having his second arm would not have changed that fact. It would have given you a better ability to show what you want to say. It is true that neither of his students turned out bad, as his tutelage has helped push both of them further.
3 He thrived without: he has become much more inventive with his jutsu
In his battles with the three Otsutsuki, Sasuke has brought out some interesting and flashy abilities. The battle against Momoshiki is easily the best in the Boruto anime so far and one of the best in all Naruto for this reason. The same can be said for the filler fight with Urashiki. While Sasuke was constantly drained of chakra it was quite annoying, he displayed some impressive abilities, such as the Kirin shown above.
two Spare Arm Needed: To keep up with the strength of Jigen and Isshiki
Both Jigen and the man housed within him haven’t gotten their hands dirty in the anime yet, but when they do, Sasuke will wish he had his extra arm. Both Jigen and Isshiki are top-tier taijutsu experts who would push Sasuke even if he had both arms, but would dominate him when he only has one. With the Otsutsuki’s abilities to negate ninjutsu, Sasuke finds himself in a bind as he can only do so much while essentially at half strength.
1 Thrived Without: Has Become More of a Historian
His loss of his arm has done more than awaken his intellectual fighting style. It has made him more of a historian. Sure, he’s still one of the strongest ninjas in the world, but he’s also one of the most knowledgeable now. His travels have taken him to many of the dimensions of Kaguya, allowing him to learn more about the Otsutsuki clan than anyone else thanks to the use of his Rinnegan. In many ways, he has become a much less evil version of Danzo.
Reference-www.cbr.com