King Lamoni’s servants believe that Ammon is “more than a man,” but they do not know what he is, or what to call him. Their use of “Rabbanah” is a respectful term that places Ammon on the king’s level, an acknowledgment of the status Lamoni has tacitly granted by confessing his hesitation to summon Ammon.
Vocabulary: “Rabbanah” is a supreme Aramaic title. The Syriac root rab means “great.” The term is used as a description of a great leader, though not always a king. (See commentary accompanying Alma 31:21.)
Finding it in the Book of Mormon text suggests a tight translation for which there is very little evidence otherwise. The evidence weighs strongly in favor of Joseph Smith borrowing vocabulary and forms from both his religious environment and the Bible. However, the evidence for close control over the spelling of names during the translation is one of the strongest arguments for a tight translation. Royal Skousen notes:
Several witnesses to the translation process claimed that Joseph Smith sometimes spelled out names to the scribe. And we find evidence in the original manuscript in support of this process. Frequently the first occurrence of a book of Mormon name is first spelled phonetically, then that spelling is corrected; in some instances, the incorrect spelling is crossed out and followed on the same line by the correct spelling, thus indicating that the correction is an immediate one.
It is not inconceivable that Joseph used a dual method of translation, with certain words like names and perhaps the Rabbanah title being represented much more closely than others.