Weapons are made to kill other people. But; not all. There are some healing weapons also. So if you know about any; from either a game, a movie, irl or just in your imagination; post it here! (;
It is weird to talk about weapons that heal, since weapons are supposed to do the opposite. Therefore, anything that heals should not be called a weapon.
Weapons kill. Only because something is called a heal grenade or a heal gun doesn't make it a weapon, it only looks like it.
But that's kinda personal definition of a foggy term, so whatever you say is neither right nor wrong...
Although, in TES:III Morrowind I could enchant for example a sword with a healing spell. It would still do the damage but at the same time heal. THAT would be a healing weapon (it only would not make sense to fight or heal with it because either your damage is crappy or you get a bounty for trying to heal someone^^)