Mutilation of captured prisoners or defeated enemies was a common practice in the ancient Near East.1 Removing the right eye would make most men unfit for war.2 When it comes to shooting a bow3 or fighting with shield,4 in either case the men would be hampered and unable to fight properly. This is why Nahash wants to remove the right eyes. In doing so, he brings disgrace upon Israel not only because many men from the half tribe of Manasseh were now maimed, but also because their maiming would testify to the weakness of Israel since they could not help their brother.
2 But Nahash the Ammonite said to them, “On this condition I will make a treaty with you, that I gouge out all your right eyes, and thus bring disgrace on all Israel.”