A merchant of death is obviously a servant of death, someone responsible for the death of others. I've heard this term before, maybe from the movies. But the popular meaning of the merchant of death are usually arms dealers. Those who profit from the sales of weapons, especially during war. There are those that made their wealth from the sales of arms, they are call the merchant of death. It is an expression well thought of because they are indirectly sponsoring the death of people with their business. The name is very catchy, it can have a deeper meaning to it too, especially when it is used as an expression to describe something else.
You can also participate by clicking here