Certainly, Shiz did not know that in spite of all his efforts, he could never kill Coriantumr. Coriantumr had forgotten the prophecy of Ether that he would survive to witness the destruction of all his people (Ether 13:21). Apparently, the Lord preserved him as a punishment. As has been said, "To a civilization fully ripened in iniquity, judgment and destruction become the kindest gifts God can give." (Michael W. Middleton, Book of Mormon Symposium Series, 4 Nephi - Moroni, edited by PR Cheesman, MS Nyman, and CD Tate, Jr., 1988, p. 194) But Coriantumr was not even worthy of death for he was to suffer the consequences of survival with a scorched conscience.
Accordingly, he survived in spite of many wounds, for he had been wounded in the thigh by Shared (Ether 13:31), wounded in the arm by Lib (v. 12), and wounded in many places by Shiz. The last of the three injuries left him in what is now called hypovolemic shock, a state in which all but the most vital organs are shut down by inadequate blood flow. That he survived such a severe injury would be surprising if it weren't for the promise of Ether that he would live to witness the fulfillment of the word of the Lord (Ether 13:21).