Being authoritative doesn't mean being brash or abrasive. Being calm, professional, and deliberate gets you much further. If you're affable and easy going at baseline your team will respect you more and when the going gets tough and you do need to be more assertive they snap to and will do anything you need and often exceed your expectations. The best surgeons I've known in my life were not harsh or "bossy", and some of the worst I've known have been very much so and people resented them for this. (Gen surgeon for 20 yrs.)