[Micah]

It takes a lot of troops in order to make fanaticism useful, since with 2 H3 priests you can fire off 3 sermons of courage plus a smite in the same 2 turns it takes for one H4 to cast a smite and fanaticism, so if your force is smaller than 3 sermons worth you're unquestionably better off with the 2 H3s, since they'll be laying down double the firepower for the rest of the battle in the case of smites, or almost double for banishment since it will scale with the extra level, but not enough to compare to 2 full H3 casts.