Isaiah 51:9–10 (King James Bible) awake awake put on strength O arm of the LORD awake as in the ancient days in the generations of old art thou not it that hath cut Rahab and wounded the dragon art thou not it which hath dried the sea
In his editing of 2 Nephi 8:9–10 for the 1837 edition, Joseph Smith changed both occurrences of the pronoun it to he. The pronoun it refers to the “arm of the Lord”; the word for arm is grammatically feminine in Hebrew, with the result that the pronoun in Hebrew is literally she. However, in English, arm is referred to by it, thus the King James translation. Joseph Smith altered the pronoun to read he, which means that Joseph semantically reinterpreted the pronoun as referring to the Lord himself, thus the use of the masculine pronoun. The critical text will, of course, restore the original pronoun it in both cases.
Having changed both instances of the pronoun it to he, Joseph Smith also decided to edit the associated relative pronouns that and which to who. These two grammatical changes were marked in the printer’s manuscript, but the first change (of that to who) was never implemented in the 1837 edition (or in any subsequent edition), possibly because it was decided that the relative pronoun that was acceptable after all. But the second change (of which to who) does appear in the 1837 edition (and in all subsequent editions) since that edition generally replaced the archaic which (when it refers to persons) with who. In most instances, the 1837 editing left the relative pronoun that unchanged but not always. For further discussion, see under which in volume 3.
Summary: Restore the original neuter pronoun it and the relative pronouns that and which in 2 Nephi 8:9–10 (“art thou not it that hath cut Rahab” and “art thou not it which hath dried the sea”).