And they don't wear Horned helmets during a battle

Hiccup had one too, but he was a viking, I guess.

Tower shields were heavy I doubt they were moved around as a weapon nearly as well as Viking shields

Romans didn't use tower shields per se. The scutum was light enough to be effectively carried in one hand and allow for the other to wield a weapon with effectiveness. The main advantage it had was the size, easily covering a legionary and anyone behind or next to him if they locked shields in tetsudo formation. Even Scutum took advantage of the handle method for a shield, so it could be used to cover the head of soldiers behind the front ranks form arrows or spears.