Sure-footed
to stumble or slip
confident competent
ex)
Pakistan making 'sure-footed' progress against terrorism: COAS
"It was a very persistent and polite but very sure-footed way of changing minds."
The second act was definitely more sure-footed than the opening one.
unperturbed 마음이 흐트러지지 않은, 냉정을 잃지 않는
not worried or annoyed by something that has happened
ex) UK festival fans unperturbed by terror threats.
Forget the threat of terrorist attacks, British concert goers are going to keep calm and carry on as usual. That’s the gist of a new U.K. report into the wants of festival fans.
http://www.theindustryobserver.com.au/uk-festival-fans-unperturbed-terror-threats/