Here the question is whether the text should read “lowly of heart” or “lowly in heart”. In this passage, the earliest extant text has two occurrences of “lowly of heart” and one of “lowly in heart”, but in the 1841 British edition, the typesetter accidentally replaced the second instance of “lowly of heart” with “lowly in heart”, probably because it was immediately followed by the example with in and was otherwise identical at the end:
Elsewhere the Book of Mormon text has only “lowly in heart”:
This usage with in also follows the King James language in Matthew 11:29: “for I am meek and lowly in heart”. On the other hand, an early revelation given to Joseph Smith, received in October 1830 (about half a year after the printing of the 1830 Book of Mormon was completed), reads “and be meek and lowly of heart” (Doctrine and Covenants 32:1), as in verse 43 of Moroni 7. Thus it appears that either of or in is possible for this phrase. For each case of “lowly of/in heart”, the Book of Mormon critical text will follow the reading of the earliest textual sources; thus here in Moroni 7:43–44 there are two instances of “lowly of heart” followed by one of “lowly in heart”.
Summary: Restore in Moroni 7:44 the preposition of in the first occurrence of “lowly of heart”; although the use of of is not as frequent in the text as in is for this phrase, it occurs invariantly in the immediately preceding verse (Moroni 7:43).