The counterbalance of her proficiency of judgment regarding one person, proved true by experiment.
Beside the young man he looked also at the photo of the lady now his 1440 legal wife who, he intimated, was the accomplished daughter of Major Brian Tweedy and displayed at an early age remarkable proficiency as a singer having even made her bow to the public when her years numbered barely sweet sixteen.
There are no more uses of "proficiency" in the book.
Show samples from other sources
Not as well as my mother, but I’m pretty proficient."
Kiera Cass -- The Heir
Yvette was by far the most competent of my coworkers, and she and I would often work together on any electrical job requiring proficiency with tools.