The terminology, "the tears of the fire" was new to Visera, she never heard about this deadly portion which can kill a dragon. Maybe it's because she was born and raised during an era where dragons didn't exist. She was stunned at this and asked, "Did you see it?" and Aurora shook her head "No".
They went on to talk more about these Dragon Hunters and how they managed to bring doom to two generations of dragons. The first time was when they brought doom to the very first king, and then when Alienor saved the dragons and his tribe, they came after Euric Morrow three hundred years later.
It seemed these Dragon Hunters were constantly looking for dragons and their existence so they can kill them. Its what they did for living, and this scared both Visera and Aurora. Now that they had truth of what truly happened to Artodo, they knew they had to stop these Dragon Hunters before they cross the Freezing Sea and cause chaos.