Isaiah 51:5 (King James Bible) and mine arms shall judge the people the isles shall wait upon me and on mine arm shall they trust
For this verse the earliest Book of Mormon text (with two singular occurrences of “mine arm”) is more consistent than the King James Bible and the Masoretic Hebrew text (both of which have a plural “mine arms” followed by a singular “mine arm”). The 1874 RLDS edition restored the King James plural “mine arms”, but this change is probably a typo since otherwise this first RLDS edition shows no evidence that the King James Bible was ever consulted in order to regularize the text for 1 Nephi 20–21, 2 Nephi 6–8, and 2 Nephi 12–24 (the major nearby Isaiah quotations).
The tendency to regularize to the singular is also manifested in the Great Isaiah Scroll found at Qumran (1QIsaÅ), which reads “his arm will judge the peoples”. Even so, the corresponding verb for “will judge” is in the plural, thus showing that the original Hebrew read arms. In any event, the tendency to regularize to the singular arm is very strong here in Isaiah 51:5, even if it ends up creating an error in subject-verb agreement in the Hebrew text.
It is possible that as Joseph Smith dictated the text for 2 Nephi 8:5, the s was accidentally lost from the first arms. David Calabro points out (personal communication) that Oliver Cowdery would have had considerably difficulty in distinguishing between “mine arm shall” and “mine arms shall”; the final /z/ of arms and the initial /sˇ/ of shall are both sibilants, so in this context only the most careful pronunciation could have distinguished the singular arm from the plural arms. Another contributing factor is that Joseph or Oliver may have expected “mine arm shall judge the people” rather than “mine arms shall judge the people”. Elsewhere in the Book of Mormon, there are five occurrences of “mine arm” (once more in 2 Nephi 8:5, twice in 2 Nephi 28:32, and once each in Jacob 2:25 and 3 Nephi 9:14) but none of “mine arms”.
The Book of Mormon text often regularizes co-occurring singulars and plurals (such as “captive … captive” in 1 Nephi 21:24–25 rather than the “captive … captives” of Isaiah 49:24–25). The same systematizing may have taken place here in 2 Nephi 8:5. In other words, the consistent use of “mine arm” in the earliest text could very well be intentional. For this reason, the critical text will retain both occurrences of the singular “mine arm”, the reading of the earliest textual sources, even though Oliver Cowdery may have misheard or misinterpreted an original “mine arms shall judge the people”.
Summary: Maintain the two occurrences of the singular “mine arm” in 2 Nephi 8:5; the singular “mine arm” works very well for both “mine arm shall judge the people” and “on mine arm shall they trust”; nonetheless, there is a distinct possibility that Oliver Cowdery misheard “mine arms shall” as “mine arm shall”.