With this perk, all custom weapon types become available to you without the schematics. Taking this perk immediately gives you the level 3 schematics for all weapon types you did not already have.
One of the weapons on Vault Boy's arms is the icon for the power fist; however, no such schematic exists to create this device. Perhaps this is just to exemplify that the perk allows you to create a wide variety of weapons.
This perk works perfectly for the Nuka-grenade and bottlecap mine. However, for all other schematics, this perk only updates the notes section of your Pip-Boy. It does not upgrade the game variables that control the quality of the items you create. You will keep producing at the level you had prior to taking this perk. If you did not have any schematic for a particular weapon you will begin producing at v1 quality. Also note, that if you acquire further schematics after taking this perk, they will only end up in your inventory and not raise your production skill.
It can be fixed using the console. You must enter the following commands:
set countRockItBonus to 1.25
set countDeathclawBonus to 1.25
set countDartgunBonus to 1.25
set countRailwayBonus to 1.25
set countShishkebabBonus to 1.25
This can be easily accomplished by copying the above text into a notepad document and saving it (into the Fallout 3 directory) as 'Warmonger.txt'. Then, in the game, type bat Warmonger into the console, and hit Enter.