The word of God is sharp to the wicked and soothing to the righteous. This is because the guilty taketh the truth to be hard, for it cutteth them to the very center (1 Nephi 16:2). To the wicked, the word of God is quick and powerful, sharper than a two-edged sword, to the dividing asunder of both joints and marrow (DC 6:2). Alternatively, to the righteous, the word of God can be as the balm of Gilead, a salve for the wounded soul, or a bandage for the broken hearted (Jacob 2:8). Therefore, whether the word is sharp or soothing depends as much upon the listener as it does the speaker. In the days of king Benjamin there were many holy men [who] did use much sharpness. But why did they use so much sharpness? Because of the stiffneckedness of the people (WofM 1:17).
Therefore, Mormon‘s use of sharpness had as much to do with his people’s spiritual apostasy as it did with his choice of words. Nevertheless, there are times when the Spirit moves a prophet, leader, or parent to use words which are sharp enough to divide asunder both joints and marrow. Such correction is inspired by charity more than righteous indignation. For whom the Lord loveth, he correcteth; even as a father the son in whom he delighteth (Prov 3:12).
To withhold appropriate sharpness, when moved upon to do so, is not an act of love but an act of Jonah-like cowardice. This is the burden of the watchman on the tower; he must cry repentance even when the mission is troubling. Jacob explained what this feels like, it grieveth my soul and causeth me to shrink with shame before the presence of my Maker, that I must testify unto you concerning the wickedness of your hearts. And also it grieveth me that I must use so much boldness of speech concerning you (Jacob 1:6-7). But in spite of Jacob and Mormon’s burdensome responsibilities, neither one of them failed in their duty to cry repentance with that sharpness which must be followed with an increase of love (DC 121:43).
Boyd K. Packer
“It is not easy to take criticism. Sometimes it is even harder to give it. But a teacher has that responsibility. If we love our students, we will do all we can to help them, even if at times it has the promise of disturbing the relationship between us. When we are called as a teacher, when we are a parent, we have that authority and that responsibility. We must use it righteously.” (Teach Ye Diligently, p. 349)
Hugh Nibley
"Their awful guilt leaps out in their instant resentment of any criticism of themselves: ‘When I speak the word of God with sharpness they tremble and anger against me’ (Moroni 9:4). They have reached that point of suicidal defiance which the Greeks called Ate, the point of no return, when the sinner with a sort of fatal fascination does everything that is most calculated to hasten his own removal from the scene—he is finished, and now all that remains is to get him out of the way: ’O my beloved son, how can a people like this, that are without civilization … expect that God will stay his hand?’ (Moroni 9:11, 14).
“Nephite civilization was thus not extinguished at Cumorah. It had already ceased to exist for some time before the final house-cleaning. War had become the order of the day, ‘and every heart was hardened’ (Mormon 4:11), with the military requisitioning the necessities of life and leaving the noncombatants ‘to faint by the way and die’ (Moroni 9:16).” (Since Cumorah, p. 400)