When you're in the middle of an important negotiation, and the other party is challenging to work with, you want your realtor to advocate for your best interests without letting ego and emotions get in the way. If your realtor becomes emotional and reactionary during the negotiation, that's when your agreement with the other party is at risk of falling apart. 

Bluster and bravado may feel right in the moment. But diplomacy, humility, and maturity are the skills you need when the stakes are high.