Speaking from authority raises some difficult problems. What if you don't have authority (yet)? You still need to project a sense that you know what you're talking about.
Authority does not come from the ego, but it is a projection of ego, in some sense. You have to have enough confidence to hold the floor. A pianissimo should not be weak. It can still be a strong, confident musical phrase. The fact that one's knowledge is limited does not mean that one's authority is nonexistent. Qualification of degree of certainty does not necessarily decrease authority.