This is the only use of the name Jehovah in the Book of Mormon. It is a holy name, a sacred title which describes the great I AM, He who is, He who causes to be, He who brings into existence. Moroni no doubt chose his words carefully so as to end this remarkable record on a note of solemn and sober testimony, a note of witness and assurance, a note of deference to Jehovah, the Lord Omnipotent.
It is to him—the God of Abraham, Isaac, and Jacob, the Holy One of Israel—that we must look everlastingly in our quest for truth and in our yearnings for peace and happiness here and for our eternal reward hereafter. And it is to him that the Almighty Elohim, the Man of Holiness (Moses 6:57), has committed all judgment (see John 5:22; 2 Nephi 9:41).
He it is that shall judge the quick (the living) and the dead. “The hour is coming,” the Savior declared, “...when the dead shall hear the voice of the Son of God: and they who hear shall live. For as the Father hath life in himself, so hath he given to the Son to have life in himself; and hath given him authority to execute judgment also, because he is the Son of man.
Marvel not at this; for the hour is coming, in he which all who are in their graves shall hear his voice, and shall come forth; they who have done good, in the resurrection of the just; and they who have done evil, in the resurrection of the unjust. And shall all be judged of the Son of Man.” (JST, John 5:25-30.)