The intent of these three verses is summarized in the final sentence of the last of the three. Jarom states: “The word of the Lord was verified, which he spake unto our fathers, saying that: Inasmuch as ye will keep my commandments ye shall prosper in the land.” When Jarom indicated in verse 7 that they were led by “mighty men in the faith of the Lord,” that tells the perceptive reader why they were successful.
Enos had declared in Enos 1:24 that he had seen “wars between the Nephites and Lamanites in the course of my days.” Jarom has also seen them, and perhaps they are becoming worse. The Nephites have had to fortify their cities and had to make all manner of weapons of war.
Perhaps more interesting is that as they spread upon the face of the land, they became rich. Specifically, they became “rich in gold, and in silver and in precious things, and in fine workmanship of wood, in buildings, and in machinery, and also in iron and copper, and brass and steel.” The obvious intent of this list is to demonstrate that their wealth was dependent upon an expertise in metals. As with our discussion of Lehi, it is unlikely that they became wealthy by simply possessing these metals—even those that we modern people esteem as precious. The metals had value, but possessed true value in what was made from them.
The word machinery in verse 8 appears to be anachronistic. That is true only if we forget that levers are also machines. The use of the word need not refer to anything anachronistic.