Here the 1874 RLDS edition replaced armies with servants; the 1908 RLDS edition restored the correct armies. This error was prompted by three occurrences of the word servants in the preceding two verses:
Of course, armies is correct, not servants; the word servant refers to a personal attendant, not to a soldier in the army.
Summary: Maintain the plural armies in Alma 47:27, the reading of all the earliest textual sources (including 𝓞).