Ideas and suggestions.

I don't see any problems with Arcomage.

They say that if you repeat the same phrase 5 times, it becomes more convincing! Let's repeat it 2 more times!:D
But in reality, you haven't encountered it, while Alex and I, for example, have faced situations where early Arcomage is practically an uncounterable overpowered unit. And even late-game Arcomage is very strong, if you think about it. Without artifacts that provide protection against magic and without upgrading units with Warlock skills. I think you understand perfectly well that getting the first speed upgrade doesn't always depend on the player... And against a Suppressor with artillery + Arcomage in the hot phase, there are almost no adequate countermeasures (the only option is to give someone Ballistics, but you also need to make sure that this hero can reach the necessary cities). Let's just say that this is a difficult option to implement in practice.