"Then am I to assume I'm the only scary thing here?" Because yes, she does, unless Eric is the only thing she has to be afraid of here. He isn't underestimating her ability to take care of herself. He simply doesn't want to underestimate the power of those individuals here.
"Until one of them attempt to see how well that smell matches up with the taste, then they will drain you without even realizing it. Being able to walk in the sun is not the only fascinating thing about your blood. The last time I was affected by alcohol was when I was human."