What Ye Xiao used was his unique technique, his Titter Phase skill. With his special Titter Phase skill, he could see things in minimum scales, especially weapons. To remove the God Slaughter Arrow from somebody's body, one must wrap the arrow with strong spiritual energy and move the arrow out bit by bit. It required caution and carefulness to make sure the arrows wouldn't break inside the patient's body. If the arrow broke inside the body, it would cause a severe injury.
However, when Ye Xiao touched the arrow in the patient's body, he knew clearly how much weight it could take. Therefore, it wasn't a difficult job for him to remove it quickly!