ethiopia wasn't technologically advanced but it was equivalent in size to the Holy Roman Empire (including Italy), so that it didn't fragment as much as the Germans and lasted for as long as it did is impressive for a bunch of Africans
I can't speak for what their actual military was like outside of Age of Empires 2 but that Nubia existed to keep the Baqt shows there still would've been some contention for Prester John to do anything in Egypt