wars create additional financial wealth, but they don't create material wealth. Wars are inflationary. The best definition of wealth has nothing to do with money, but instead asks what the productive potential is. Wars decrease productive potential. They may increase it for one society and decrease it for another, but the sum total is reduced. There are interesting questions here about the destruction of low productivity facilities, say a factory of weavers, versus destruction of high productivity facilities such as a factory of weaving machines.
Also, some wealth is lost in the form of bullets, bombs, and other weapons that are used in the process. It's not the total cost of the bomb, but it is the cost of the physical material that makes the bomb.