If Snape made Sectumsepra and he knew the counter-course (vulnera sanentur), and Snape accidentally hit George Weasley with the curse, why didn't Snape heal him?
He couldn't heal him in two seconds, while in a duel with countless other people IN THE SKIES. I don't think that after he really had the contact to heal him
^that, and it would have been very suspicious for a "death eater" who was "faithful" to voldemort to go and heal a member of the order assisting harry potter (or in his case basically being harry potter)
"Though the aforementioned healing spell may have healed the wounds and essence of dittany may have prevented scars, any body parts that had been severed by this curse could not be grown back (a trait of dark magic's permanent effects), as demonstrated by George Weasley when he lost his left ear to the spell"
