Auto-translated
So, what's the justification for angels in the Castle faction? It's just mindless borrowing from Heroes of Might and Magic III. Nothing more. Where else do angels fight on equal footing with humans and rank slightly higher than cavalry in the hierarchy? It's absurd. Even in my favorite Heroes of Might and Magic III, I don't support the developers' introduction of this unit. :(
Devils are a different story. All their subordinates are also from the Underworld (including imps, nightmares, and succubi). But angels don't walk the earth, so there's no reason to include them among humans.
It turns out that Heroes of Might and Magic V isn't perfect in terms of faction distribution either.