In his editing for the 1837 edition, Joseph Smith felt some awkwardness in “woe unto whom he shall say this”, and he therefore inserted the words him to before the relative pronoun whom. Elsewhere in the text, we have 28 examples of “woe unto X” that are postmodified by a relative clause. There are, for instance, three other examples in the book of Helaman:
But there are no other examples like the earliest text in Helaman 12:22 (“woe unto whom he shall say this”), which suggests that this reading without him to could be an error. Perhaps him to was accidentally omitted when Joseph Smith dictated the text to Oliver Cowdery or when Oliver copied the text into the printer’s manuscript (the original manuscript is not extant here). There is evidence elsewhere in the Book of Mormon text for Joseph’s emended language:
There is also an example of this same phraseology in the King James Bible:
Nonetheless, the original text here in Helaman 12:22 is not that difficult to understand. Moreover, there are examples in the King James Bible of “(un)to whom” for which there is no explicit antecedent, just like originally here in Helaman 12:22. Here is one example of where we get “to whom” rather than the expanded “unto him to whom”:
In examples like this one, the whom is equivalent to the relative pronoun whomsoever; that is, the whom acts like a universal quantifier. In the same way, the earliest reading for Helaman 12:22 can be interpreted as equivalent to saying “woe unto whomsoever he shall say this”. The critical text will therefore restore the original usage in Helaman 12:22 since it will work.
The possibility that whom here in Helaman 12:22 is actually an error for whomsoever seems highly unlikely. There is no evidence in the history of the text, including its early transmission, of who(m)soever and who(m) ever being mixed up. On the other hand, there is evidence of mixups in the printer’s manuscript between whosoever and whoso. For discussion of those cases, see under 3 Nephi 11:23 and Ether 10:6.
Summary: Restore the original text in Helaman 12:22: “and woe unto whom he shall say this”; here the relative pronoun whom is equivalent to whomsoever and does not need any explicit antecedent, as in many examples in the King James Bible.