The sword of Laban became a symbol of the Lord's power to preserve the righteous. It was built of fine materials and was later used by Nephi as a pattern by which he made more swords for his people (2 Nephi 5:14). Laban's sword was preserved by the Nephites and passed down with the holy records to the days of Moroni. DC 17:1 reveals the promise that the three witnesses of the Book of Mormon would get the privilege of seeing the sword of Laban. That this promise was fulfilled was attested to by the testimony of David Whitmer (see commentary on the testimony of the three witnesses).
"In Jerusalem around 600 B.C., the powerful Laban was slain by the young Nephi with Laban's sword. Nephi then brought the sword with his father's family across the ocean to the Americas. The sword was revered in Nephite history and preserved until the nineteenth century, which hints at the importance of the blade…. Nephi 'did take the sword of Laban, and after the manner of it did make many swords' (2 Ne. 5:142 Ne. 5:14). … The sword is also only mentioned by the Nephites three times after that, which 'suggests that the weapon was not only well known, but also unique, wielded by kings, with no comparable weapon being used by others.' In this sense, the sword was strictly part of the regalia and was not used or handled by any individuals beside the king.
"Held by the Nephite kings and leaders, the people saw the sword of Laban as a religious symbol and a sign of the leader's kingship and power….The scant references to the sword of Laban in the Book of Mormon are all associated in some way with victory.
"The sword of Laban was preserved through the centuries along with the plates, the Urim and Thummim, and the Liahona, items which formed a collection of sacred relics. These sacred implements were passed down by the leaders throughout Book of Mormon history. Of these 'national treasures a real king was required to possess anciently,' the sword of Laban was 'a symbol of power and rule.' When King Benjamin transferred 'charge concerning all the affairs of the kingdom' to his son Mosiah about 130 B.C., he also bequeathed the sacred relics, including the sword of Laban (Mosiah 1:15Mosiah 1:16Mosiah 1:15-16)." (Brett L. Holbrook, "Alma 17:37Alma 17:38Alma 17:39The Sword of Laban as a Symbol of Divine Authority and Kingship," FARMS Journal of Book of Mormon Studies, vol. 2, no. 1 (Spring 1993), 53-4.)