The tool (pellet gun) is not the problem. Stop blaming the tool. Blame the attacker. The kid will probably grow up and sling sulfuric acid on his girl friends face. When he does that, will that be the acid's fault, or the shopkeeper who sold the acid, or the company that manufactured the acid... no it'll be the attacker's fault.
I have a pellet gun and kids. They all use it responsibly and enjoy doing so. They would never shoot someone with it or threaten anyone... they know better.