As Jesus concludes his private discourse to the twelve he returns his attention the larger group. He addresses them and indicates that “ye are weak.” Their “weakness” is that they “cannot understand all my words.” It probably is not from lack of desire or attempt. It is probable that it is sheer physical weakness, as they have been listening to Jesus for a long time. The experience of his arrival was dramatic, and intense spiritual experiences can be physically enervating. The people are quite simply tired, and the Savior recognizes this.
Translation: Joseph Smith was quite inexpert in the use the Elizabethan forms. In this case, he has Jesus address a multitude with “ye,” which is the second person singular, or the individual “you.” Certainly Jesus was addressing the complete body of people, and not a single person. The translation ought to have been “you are weak” to be grammatically correct. However, Joseph was imitating a form for which he did not understand all of the rules. That he should make such a grammatical error is quite understandable, as most of those who recognize the error in English are those who have become sensitized to this type of form in a different language.