Secretary onee-san is about to hero-chan a nice big slap of reality. Angelica's naivety would be fine if she was just a little village girl, but she's the one and only hero and her viewpoints can easily affect the lives of millions for generations. Instead of trying to talk to the demon lord, she immediately tried to slay the peaceful man. If demon lord wasn't so kind, she and her party would have been annihilated, her kingdom left in ruins, humanity enslaved, etc.