According to Brant Gardner, the extant artistic representations of Mesoamerican warfare suggest that the visual presentation of the army may have been an important aspect of warfare, and specifically designed for intimidation. While the intimidation of the Lamanites was created by a difference in armor, intimidation in later years was attempted by visual displays in addition to the armor.
The most exciting visual display of this visually impressive armor/intimidation is found in the manner warriors are shown in elaborate headdresses and body clothing/armor made of jaguar skins. The importance of military presentation and intimidation reached a pinnacle among the Aztec warriors. Tributary states were required to supply military "suits" which can be seen in all of their impressive glory in the Codex Mendoza folios 19-41 and others.
In later times the modes of intimidation increased, including the sounding of trumpets to increase the noise, and probably to invoke the sounds of the divine. The jaguar costumes that we see so often in Maya paintings were certainly used to invoke the power of the jaguar in behalf of the warriors. This short scene in the Book of Mormon is quite at home in the Mesoamerican location. [Brant Gardner, Book of Mormon Commentary, [http://www.highfiber.com/~nahualli/LDStopics/Alma/Alma43.htm], pp. 15-16]
“Armor”
The term "armor" appears in Alma 43:21 as part of the Nephite defensive strategy. There are eight distinct terms for armor mentioned in the Book of Mormon: breastplate (11 times), shields (10 times), armor (9 times), head-plates (7 times), arm-shields (2 times), animal skins (2 times), thick clothing (2 times), and bucklers (1 time). . . . According to William Hamblin, if Joseph Smith used the Bible as a major source for plagiarism when inventing the Book of Mormon, as many critics claim, we would expect the major terms for armor in the King James Bible to appear also in the Book of Mormon. In fact, this is not the case. Rather, Book of Mormon armor terminology differs from that of the King James Bible in precisely the terms for which Mesoamerican armor has no counterpart. We find that three biblical armor terms are not used in the Book of Mormon: coat of mail, greave, and helmet/helm. Likewise, three Book of Mormon armor terms are not found in the Bible: arm-shield, head-plate, and thick clothing.
The KJV coat of mail is a mistranslation of the Hebrew which should properly be rendered as coat of scales: a leather jacket on which are sewn numerous small plates of metal. Such armor was in widespread use in the Near East in the seventh century B.C., but was unknown in ancient Mesoamerica. Coat of mail is the King James Version term used to describe the armor of Goliath in what is undoubtedly the best-known combat story of the Bible (see 1 Samuel 17:5). As such, the term would have been quite familiar to Joseph Smith, yet it never appears in the Book of Mormon.
The greave, was a special type of leg armor used to defend the shins of the lower legs. Although the Maya did wear a type of anklet that could be considered a greave, most Maya artwork clearly shows the legs as essentially unarmored.
Maya head armor could, of course, be called a helmet, as is done by most archaeologists. On the other hand, the structural differences between a Near Eastern helmet, which was a single piece of metal formed to rest on the head, and the Maya headgear, which consisted of many small plates mounted on cloth or wood, should be enough to justify the difference in terminology. [William J. Hamblin, "Armor in the Book of Mormon," in Warfare in the Book of Mormon, F.A.R.M.S., pp. 404, 416-418]
Alma 43:21 Armor ([Illustration]): Comparison of Biblical and Book of Mormon Armor Terminology [William J. Hamblin, "Armor in the Book of Mormon," in Warfare in the Book of Mormon, F.A.R.M.S., p. 417]