By who? The Purebloods who see him as an ally aren't afraid of him. But yes, in Hogwarts - see Eliezer's response here. I don't know how Snape compares to artifact-holder Moody (who seems more likely to scare Death Eaters). Severus outranks dueling champion Flitwick in power (according to the reference in that thread) but Moody would tell you not to trust duels as a measure of combat readiness.