Talk:Myrtenaster/@comment-68.200.79.18-20160720195816/@comment-410526-20160720200734

The hammer is a part of the firing mechanism of a gun. You pull back the hammer (called "cocking" the gun) which compresses a spring device. When you pull the trigger the spring asserts itself quickly and causes the firing pin to impact on the primer of the bullet, igniting the gunpowder in the cartridge.

In other words, it's the bit of the gun that goes "click" in the movies when you know someone is getting serious.

That's what that image is referring to. Myrtenaster has a hammer and trigger mechanism that ignites the Dust, like a gun (it's based on a revolver).