I've heard critics describe Nephi's steel bow as an anachronism. Apologists have suggested that it was likely a wooden bow adorned with or reinforced in places by steel components.
As I was studying about the Ark of the Covenant last week, I was reminded that it was not made out of solid gold (sorry, Indiana Jones).
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According to the Old Testament, the ark was constructed of acacia wood (commonly known as thorn trees) and adorned with gold.
Perhaps there is something analogous here?