Moroni’s reference to having the Lord give grace to the Gentiles returns to the statement in verse 26, that his grace is “sufficient.” What Moroni is saying is that the Gentiles need to understand the message of the Book and he prays that they will be in such a state that the Lord’s grace might be “sufficient,” or that it might help them to obtain the blessings inherent in passing the test and accepting the Book of Mormon.
[that they might have charity]: That they might accept the Book of Mormon in spite of its weakness in writing. This is the “tolerance” or “good will” definition of charity rather than the “love” definition.