He was dressed in a white shirt worn buttoned to the throat and gray, neatly pressed trousers. His figure, especially the neck and shoulders, communicated the impression of irrefutable physical strength, and of precise, even imperial bearing. Kabuo's features were smooth and angular; his hair had been cropped close to the skull in a manner that made its musculature prominent. In the face of the charge that had been leveled against him he sat with his dark eyes trained straight ahead and did not appear moved at all (Guterson, ch.1).
What does the word imperial mean in this passage?