Another hand salute?

[Tarbicus]

Removing one's helmet when in the presence of a god or his image in a shrine would be akin to going bareheaded into a church--a sign of humility and respect.

Removing ones helmet when going before a high superior, such as one's legate or tribune, proconsul, or emperor, would be the ultimate show of subservience as you are removing the one truly vital article of protection. The removal of the helmet would show your loyalty to him and your trust.

That might not be how it was, if you read the thread. The head was covered while praying and paying homage to the gods. When hailing a mortal it was wise to uncover the head to avoid the danger that the gods would think that mortal was being held with the same esteem as them. So it's kind of the other way around, where the Roman practices were opposite to modern church ones.