It seems to me that by itself Sun/Mars aspects are likely too boost competiveness, assertiveness, etc., but the kind of aspect would point to control or lack of it. For instance, a trine should add stability, so smooth power, but a conjunction would point towards explosiveness, a square even more so. With a hard aspect it would have to be mastered, the energy.
You would have to look at way more than this one aspect to get an idea of whether a person would be brave, or just obnoxious, or worse.
