Ralph Leonard Foster argues that the name "Moroni" is borrowed from the Italian name "Moroni."
Ralph Leonard Foster, The Book of Mormon on Trial: An Unaccepted Challenge Presented to Mr. David O. McKay President, Prophet, Seer and Revelator and The Council of the Twelve Apostles The Church of Jesus Christ of Latter-day Saints Salt Lake City Utah (Kamath Falls, OR: Ralph L. Foster, 1963), 16
Now concerning this person Moroni, where did Joseph Smith obtain a name for his principal angel, out of the 350 names mentioned in the Book of Mormon, over 100 can be found in the Bible (Brodie, p. 73.) Since it didn’t bother Smith to do a little plagarizing in this matter of names for his characters, would it be unusual if he borrowed someone’s name for his angel? No writer that the author read mentions this fact, so he decided to do a little investigation on his own.
Actually Moroni is a good Italian name, although it is not common. By searching through a number of recent telephone books I noticed the name occurs twice in the Sacramento directory, three times in the Seattle book, three in Los Angeles and one in northwest Nevada. My next door neighbor is an immigrant from Italy who verified the fact that Moroni is a good Italian name. Frederico Moroni is a living Italian painter who heads the famous Scuola di Severino of Bornaccino, Italy. (School Arts, May, 1963, pp. 12-16.) The thing which struck the author full force was the fact that there was an older Italian painter by the name of Giovanni Battista Moroni whose portrait of Galileo was exhibited at the Boston Atheneum in 1829, the year Joseph Sith began his Book of Mormon. (See Photo 3). Whether or not Smith actually saw the portrait of Galileo is unimportant to me. The fact that he could have read about the 1829 exhibit, or head about it, is significant in itself. Giovanni Battista Moroni (1525-1578 AD) was a noted painter, not a few of whose portraits grace American galleries. His “A Gentleman in Adoration Before the Madonna” is in the National Gallery, Washington, D.C., and his “Portrait of Bartolomeo Bongho” is in the Metropolitan Museum of Art, New York City. There are others besides these in American collections. Moroni’s well known “Portrait of a Tailor” appears in “World Famous Paintings” by Rockwell Kent, the original of which hangs in the National Gallery, London, England, Miss Rosalind Lawrence, Department of Paintings, Museum of Fine Arts in Boston, sent me a print of Moroni’s “Count Alborghetti and his Son” which hangs in the Boston gallery.