Here the Book of Mormon text has did rather than the didst of the King James Bible. The Hebrew underlying the King James text uses a participial phrase to express “which did(st) weaken the nations”, with the meaning ‘the one weakening the nations’. In older English, the inflectional form of the verb in a relative clause was made to agree with the antecedent of the relative pronoun, thus “thou ... which didst weaken the nations”. In modern English, the tendency is to favor interpreting the relative pronoun as a third person form, thus “which did weaken the nations”. We can see how this tendency could arise by noting the many more examples of a relative pronoun being followed by did rather than didst. Excluding this example in 2 Nephi 24:12, we get the following statistics for the original text of the Book of Mormon:
which did | 42 |
who did | 19 |
that did | 14 |
which didst | 0 |
who didst | 0 |
that didst | 2 |
The two examples involving didst are found in a later Isaiah quote:
Notice here that thou, the antecedent for the relative pronoun that, comes immediately before; thus there would have been less of a tendency to change the text to “thou that did not bear … thou that did not travail”. In 2 Nephi 24:12, on the other hand, the antecedent thou does not immediately precede the relative pronoun; instead, the immediately preceding noun is ground, which may have been the reason that didst was replaced by did, perhaps even accidentally in the earliest transmission of text. In other words, there appears to be a proximity effect at work here in 2 Nephi 24:12. The critical text will maintain the use of did since it is not particularly offensive (note that no edition has ever restored the King James didst in this passage). Nonetheless, it is quite possible that the occurrence of did is an early transmission error in the text.
There are a number of examples of thou in the earliest Book of Mormon text for which the verb is lacking the -est ending:
These examples provide additional support for the Book of Mormon reading “thou ... which did weaken the nations” in 2 Nephi 24:12. See the discussion under 1 Nephi 14:8.
Summary: Retain did in 2 Nephi 24:12 (the earliest extant reading), even though it may be an error for didst.