What is significant about Sohrab being the one to stop Assef?? AND How is is accomplished?

The fight between Amir and Assef is surreal not just because Amir does not remember everything clearly, but because it is an echo of his confrontation with Assef when they were children. Years before, Hassan saved him with his slingshot and now, Sohrab saves him with his. Even the way Sohrab defeats Assef is eerily similar to the way Hassan threatened him-Hassan had aimed the slingshot at Assef's eye once before, and now Sohrab finishes what his father began.

I personally believe it to be significant because once again Hassan is saving Amir. Granted, it's his son this time, but it goes to show a sense of redemption for Amir. Despite how he betrayed Hassan, Hassan forgave him and his own son saved his life. It's significant in the sense that the line of goodness that was in Hassan was passed down to his son. Both of them wound up saving Amir and teaching him what it was to truly love.