Usage patterns
〈人〉に威厳があるsomeone has an air of dignity
The principal had such dignity that the students naturally straightened up.
威厳を保つto maintain one's dignity
The king maintained his dignity even in a difficult situation.
威厳を示すto display an air of dignity or authority
He conveyed his dignity through a calm tone of voice.
威厳を失うto lose one's dignity/authority
The prime minister lost his air of authority because of that careless remark.
Expressions
威厳のあるdignified; majestic; stately; commanding