Little Froggie, you mentioned that Dovid Hamelechs army...constituted Talmidei Chachomim of repute...`
Certainly some of them were. Others, though, were not even Jewish, like Ittai HaGitti and his 600 men who were from Gat, making them Plishtim, Like the Kraisim and the Plaisim, like the allies from Tzor that eventually became not only allies but builders of the Beis Hamikdosh under Shlomo Hamelech. Kings used mercenaries – in fact, where there were no standing armies, only tribal levies as described in Yehoshua, Shoftim, and Shmuel, mercenaries were vital bodyguards for Dovid Hamelech and others after him.
Kings used relatively unlearned farmers and shepherds when the need arose. And they used Talmidei Chachomim as well.
Our yeshivas need to teach more Neviim and Ksuvim so that our received wisdom doesnt contradict our holiest and oldest writings.