A water sprite is a mythical creature who is known for their beauty and gracefulness, so the simile is used to describe the vampire's movements.
Consider the statement "Even though Santiago wasn't convinced, he turned his attention to the vampire who was pacing back and forth in the cellar, and her movements were graceful.". Based on this "Santiago wasn't entirely convinced, but he turned his attention to the beautiful vampire, who was busy pacing from one end of the cellar to the other, her movements like a water sprite." a true statement? Yes, no, or I don't know?