I think what we read in the Captain Moroni scriptures is a combination of temporal and spiritual wisdom. For example, Moroni relied both on spies and on Alma to give him vital information. Teancum "saw that the Lamanites were determined to maintain those cities which they had taken, and those parts of the land which they had obtained possession of; and also seeing the enormity of their number, Teancum thought it was not expedient that he should attempt to attack them in their forts. But he kept his men round about...yea, and he truly was preparing to defend himself against them, by casting up walls round about and preparing places of resort." (Alma 52:5-6) How did Teancum know what to do? How did Moroni know how to defeat the Lamanites, given the recorded words of Alma and information from the spies? I think Moroni's training was primarily on the job - he was, after all, called to be a general in his twenties.