The quote in _The Hobbit_ refers to Goblins as having invented all sorts of the awful weapons and instruments of torture that have plagued history. From the context, it does not specify that the goblins had invented them by the time of the action of the book: in _The Hobbit_, Tolkien did not make a radical break between the book's history and our own as he would with the LR.

: There are references to 'blasting powder' made during the Battle of Helm's Deep. I assume it to be some form of black powder. It seems that at least Saruman had figured out how to make it, however there were no reports of Uruk-hai picking off defenders with matchlocks :)

This pretty much follows our history, where the Chinese first invented gunpowder, using it in rocket fire work tyoe displays (so maybe Gandalf, renowned fireworks artiste, also knew of gunpowder?), then it was used for heavy cannon, and only much later for firearms individual soldiers could carry.

I'm glad the title of this thread has been changed: weapons of mass destruction are either nuclear, chemical or biological weapons. In Middle-earth there was indeed a weapon of that league, the Ring of Power, natch.