Originally I think it was monks in Frankia that wanted to demonise the norse people who frenquently raided monasteries in Irland and the British isles. The monks who who lived in these monasteries didn't really have that much time to describe warriors that looked like, well, warriors! They had been at it since the 500s, but it wasn't until Lindisfarne that the Frankish rulers set the propaganda machinery to work it's magic on the vikings. To begin with, they claimed they had horns. But in the romantic era of the 1800s, Vikings, Gauls etc. got the horns replaced with wings because they wanted these "noble savages" to be more "noble". The Franks where bloody good at it because many daft bastards are keeping this myth alive today. They've got a blood eagle coming their way.

In reality their armour looked like any other northen european armour from that age.

Now, I'm sort of fine with people not knowing shit about scandinavian history, and I'm also fine with rewriting history to serve a purpose, but just doing it wrong because you're lazy is just utterly, utterly daft. I mean, bloody hell, this rubbish is on Discovery and the History channel! If I ever get the chance I'll start a myth that the indians or soldiers in the american civil war wore thick makeup.