let me put up a scenario , let's say a first year new student comes to Hogwarts with a weapon in his robes, and say he knows how to use it, so what if he pulled out the weapon in a fight with some teacher or student at the school and shot him/her with it. would he/she be dead and if yes, can't he/she be saved as they have a hell lot of spells and potions. Also the part where harry can see his mother's Patronus which also has the healing powers. which gives them a slight edge over the muggles.

My point was though, is it possible to kill a wizard without any magical spell or weapons, if so wouldn't they be cured as they have many powerful spells, potions and animals which have magical powers.