“Hiss” seems like a confusing word in the King James Version. Gileadi translates it as “summons,” and the NIV uses “whistle.” But the meaning is clear: Yahweh calls all nations to his ensign. The righteous will correctly interpret his catastrophic judgments as an ensign to the righteous. The theme of the ensign reprises the opening of chapter 12.
Comparison: 2 Nephi Isaiah ends this verse with “none shall be weary nor stumble among them.” The phrase appears at the beginning of the next verse in King James Isaiah. The Book of Mormon verse divisions were, however, added in the 1879 edition so this provides us no information about the original text. The location makes no difference in the meaning.