Everyone can benefit from being diplomatic. You can reduce fallout from people spreading false rumors about your for example. Remaining calm and courageous definitely helps in stressful situations. Accepting whatever situation you happened to be in without denial is an initial step. I agree that being unphased against open hostility is essential for diplomatic conversation. Throwing water on the fire shows a self-disciplined position of civility.

"COURAGE   Confrontation brings us peace, resolution to conflict, and personal progress. Courage enables us to confront beliefs, confront fears, and confront opponents such as bullies. If you cant handle the truth, you live in fear of the truth. If you live in fear, you don't live well. To live, face your fears. If you can't confront your fears, your fears instead may confront you when you are unprepared. To seek God, you may first need to face your fears. Confrontation is an opportunity to resolve conflict. Hesitation in conflict decays our energy and burdens us with stress."
.. "We can test faith in others with the courage of releasing our inhibitions as worrying about what others think of us, and present our authentic unique self to others, trying a unity of acceptance rather than popularity. Sometimes the greatest fear, is fear itself. Sometimes the greatest fear is the truth. When you are governed by fear, you are governed by evil. At some point in your life, the sooner the better, confront each of your fears. Confronting our fears brings us to a higher existence... with life, truth, love, and peace. So, there is reason to welcome a conflict and enjoy a new phase of life."

"COMMUNICATION   Communication is like a key to any person's door.   Conversation. In a one-to-one conversation, if you are talking more than half the time, consider to listen more. If you are talking less than half the time, consider to speak up more. Interruption is to be avoided unless someone is wrongfully dominating a conversation or you believe you already know what they are going to say." ... "When you criticize someone, don't speak to their personality, but rather to their behavior. Criticizing personality lowers self-esteem more than criticizing behavior, and may work against a resolution instead of towards one. The truth hurts, and most of the time the truth should be spoken, but make the truth hurt less when you can.   Tempered Voice. To encourage clarity while avoid rambling communications, it may help to tamp down each thought and share it only if re-emerging with clearly, avoiding a stream of consciousness. Such a voice may be a voice for teaching, diplomacy, and focus.   Untempered voice is a stream of consciousness. To connect with someone in development of trust and unity, there may be a time to speak without concern of harsh judgment from others." ... "Persuasion. You can take great stress in pushing someone to your will. Or, you can take great relief in offering them information they can freely accept or reject."

Snippets from https://rainbowrock.rainrd.org/ Rainbow Rock open book website.