appearance or behavior that fits an important person — as in "She has a magisterial manner."
of something written in a comprehensive manner by a respected authority — as in "a magisterial account of The Great Depression"
relating to a government authority (or specifically to a magistrate who can administer the law) — as in "It is within her magisterial district."
offensively self-assured or given to exercising unwarranted power — as in "managed the employees in an aloof magisterial way"
She was a widow, a chameleon lady who worked in her flower beds in an old straw hat and men's coveralls, but after her five o'clock bath she would appear on the porch and reign over the street in magisterial beauty.
magisterial = fitting for a person of importance
There are no more uses of "magisterial" in To Kill a Mockingbird.