Complex sentence: In general, he is "imperturbable, omnicompetent, firm but genial, and an accomplished actor"; commands authority but does not prove particularly effective in his administration of the law, giving rise to doubt about the justice system in the novel.
Split into simpler sentences: In general, he is "imperturbable, omnicompetent, firm but genial, and an accomplished actor", who commands authority. However he is not particularly effective in his administration of the law, and this leads to doubt about the justice system in the novel.