If you describe someone's behaviour or work as magisterial, you mean that they show great authority or ability. his magisterial voice and bearing The Cambridge World History of Human Disease is a magisterial work
used of a person's appearance or behavior; befitting an eminent person; "his distinguished bearing"; "the monarch's imposing presence"; "she reigned in magisterial beauty"
offensively self-assured or given to exercising usually unwarranted power; "an autocratic person"; "autocratic behavior"; "a bossy way of ordering others around"; "a rather aggressive and dominating character"; "managed the employees in an aloof magisterial way"; "a swaggering peremptory manner"