"I want to say that the reason why the Fake Monk has an amplifier but the others don't is because the tech is limited since, after all, the Thunderchild crew are just a bunch of annoying pirates.
"

Just because you don't CURRENTLY have the resources to reproduce an overpowered technology doesn't mean you won't always. I'm not going to give you an overpowered technology, let you guys raid one base successfully to get materials, and then produce a superweapon capable of leveling the world.