First, do you really think people creating weapons of war would bother obeying the GPL?
Sure, most weapons of war are created by companies which act within the law in order to do so.
A broader question is: I don't think you can revise the GPL, can you? If you change the GPL it's no longer the GPL referred to by the GPL when the GPL says that anything produced with the GPL must be licensed under the GPL, thus all existing GPL software will still be under the old GPL not the new GPL.
You'd have to start from scratch with a new licence and develop a new codebase.
The FSF publishes new revisions (see: GPLv3). Some projects are released strictly under GPLv2 (e.g. Linux), but it's more usual to release software under "... or, at your option, any later version published by the Free Software Foundation".
Sure, most weapons of war are created by companies which act within the law in order to do so.
A broader question is: I don't think you can revise the GPL, can you? If you change the GPL it's no longer the GPL referred to by the GPL when the GPL says that anything produced with the GPL must be licensed under the GPL, thus all existing GPL software will still be under the old GPL not the new GPL.
You'd have to start from scratch with a new licence and develop a new codebase.