Here the sword of Laban is a model for other weapons. Nephi mentions nothing more about his sword-making than that the swords were "after the manner" of the sword of Laban. It is not clear what this means. Certainly there is a lack of archaeological evidence for swords that would match the "manner" of an Old World sword.
We know that Nephi was early able to work metals. His experience forging tools for the ship would have remained with him, and the plates upon which he writes are another evidence of the continued use of metals. Therefore it is possible that the sword was also metal - although it is not necessarily required by the text. In order to make a sword similar to that of Laban, the particular metals and methods would be required, and they may not have been present.
On the other hand, Nephi may also have written in a general sense: he made the Nephites' weapons on the general pattern of Laban's sword--a hand-held weapon with a double-edged long blade--rather than exactly copying its structure and material in every detail. And in a general sense, the macuahuitl has many parallels to a typical sword." (WARFARE IN THE BOOK OF MORMON, Page 345)
The archaeological information on the Mesoamerican "sword" provides a possible meaning for the "sword" of the Book of Mormon (though not absolutely certain for the swords modeled on the sword of Laban.) The weapon that bears the Nahuatl name "macuahuitl" was a wooden shaft with obsidian blades on both sides. While that does not visually match our conception of a sword, it does fit relatively well with the descriptions of the way swords were used in the Book of Mormon.
Because superior military technologies provide a marked advantage in early warfare (as witnessed by the Spanish sword in combat with the Aztec macuahuitl) it would be expected that any accurate copy of the sword of Laban, particularly in quantities, would first give the Nephites a military edge, and secondly be rapidly incorporated into other cultures. For this reason alone, it is therefore suggestive that "after the manner of" does not necessarily translate into the same materials. If an inferior metal were used, the sword might lose the edge, or be too brittle for use.
Whatever the reason, while the original defensive weapons of the Nephites were modeled on the sword of Laban, history suggests that they were replaced with other types of weapons. The only reason that would happen is if they other weapons were actually superior. The suggestion again is that the copies were not of the quality of the original.