Imagine you are at a debate on a controversial topic. One of the speakers presents her case straightforwardly and with conviction; there is no doubting her stance on the issue. At the same time, you are struck by how politely and tactfully she addresses this divisive topic. Is there a single word that might describe such a combination of traits?
This is what psychologists call assertiveness. Here's how wiki starts its entry:
Assertiveness is the quality of being self-assured and confident without being aggressive. In the field of psychology and psychotherapy, it is a learnable skill and mode of communication.
However, not all general-purpose dictionaries are up to date and seem to define assertiveness in an opposite way. Here's what The Free Dictionary says:
Inclined to bold or confident assertion; aggressively self-assured.
Merriam-Webster is sort of treading a middle course:
[D]isposed to or characterized by bold or confident statements and behavior