"It has an imposing presence." "威容" means an imposing presence or a noble presence. This is mostly a word for an object. For a person, some other words should be applicable. The basic meaning of "誇る" is "proud of". But in this case, just meaning "it has". The use of "誇る" here is so unique and distinctive that I can't explain very well. "威容がある" means totally the same thing. However, if you want to make it more brilliant or more exaggerated, you can say "威容を誇る".

to show your impressive and dignified manner~

I need some context here. This one is hard.