While there is a long history of regulation of guns, and there are some examples of demonization of other categories of arms in the 19th century (such as Bowie knives), the earliest example that I can find of demonization of guns is a 1960 court decision from New York that compares a handgun to the serpent in the Garden of Eden, tempting the owner to misuse it.
He’s looking for further examples. If you know of any, head on over there and comment. This should be an interesting scholarly work. I’m not convinced that demonization of weapons has ever had so much to do with the weapons themselves, so much as hatred and fear of the types of people that elites believe carry them. In the past, it was hatred and fear of racial or ethnic minorities. We’ve advanced much as a civilization since then, however, and reserve that hate and fear now for cousin humping rednecks.