This fight is actually pretty easy; its seems intimidating at first but I promise its not that hard. Although it would make more sense to split up the swordsmen and choose the hero path; I found this much easier going the legend route. You have 2 less fights to bring down your score and you actually fight less enemies in the long run. Going the legend route you will fight all 6 swordsman at once in a mob battle using Gai as your main character and Lee and Sakura as your supports.
Use dynamic entry + a lot. You can usually catch multiple enemies in the attack and it does decent damage to all the enemies it hits. Have some chakra replenishment items on hand so you don't have to waste as much time charging up your chakra. There is a small invincibility frame when you are finishing off one of the swordsman, so you can charge straight to one if they are ready to be knocked out. You press right next to them (It will have prompt above their head) to finish them off. This also resets your location on the battlefield giving you a chance to locate an enemy before they can strike from off screen. Burst attacks + + are very helpful as once its activated the only thing that can stop it is you failing to press the right button in time. This attack allows you to attack multiple enemies without being touched.
When using taijustu (punches and kicks) make sure to use rear attacks. A rear attack is triggered when a button prompt comes up on your screen telling to press . This puts you behind an enemy and allows you to continue your combo. This not only pulls you out of harms way but is effectively making hand to hand combat much easier. Once all 6 are defeated you will move to Kakashi's fight with Zabuza and Haku.
The fight with Zabuza and Haku is not that hard. Its a normal fight so none of the mob battle stuff will show up here. Just smart; use substitution jutsus wisely to avoid his ninjutsus. Make sure to use substitution jutsu when he attempts his hidden mist jutsu; this will get you a secret action which will help your score for the s rank. The major sticking point for this fight; was the quick time event where the 2 water dragons meet and you have to press rapidly. It requires you to do it so fast its ridiculous. Honestly get that out of the way right away by doing ++. If you fail more then once start the fight over; you only go back to the beginning of this fight not the entire thing. Once Zabuza is down to a certain point in his health bar a series of quick time events start; get these right the first time to avoid losing health and you should be fine to have your s rank.