Originally posted by Silent Master
That was at the end of the fight where Thor was starting to get annoyed, hence him denting Iron-man's suit with a headbutt and crushing it with his hands.
I'm wondering about him knowing about Cap's shield and wanting to test it after Heimdall prolly saw Cap fight Loki and told Thor about it. I don't think Thor would have done that knowing otherwise. He really isn't in the business of killing humans.