Black-capped Hammer

The Black-capped hammer is the common insignia of any worker, that has finished their apprenticeship. Together with a toolbelt, a worker finishing their apprenticeship crafting task gets awarded a hammer that was usually forged by their master. The hammer may vary in form and size, but they always had a black cap at the end of their haft, giving the name to the item. On top of this cap, the master would imprint his guild's insignia.
Over the centuries, different crafting disciplines have copied this tradition with their own tools. Crafting disciplines using a hammer often differentiate their hammers with a colored band around the haft. Additional colored rings in specific order from top to bottom may denote the hometown of the worker, special recognition they were granted by a patron or even the rate at which they were willing to work for. This marking is a language in itself and often varies greatly between different regions.
The Black-capped hammer has become a way of members of the Steelbrethren to communicate their allegiance to each other. There are currently four different versions of specific markings on these hammers around, as the movement needs to stay ahead of the intelligence officers of the government.

Additional information

With the rise of simple work and fast apprenticeships within factories, the cap usually holds the factories' symbols instead of a guild's symbol. Guild masters are protesting this trend vehemently, especially, since the given hammers are cheap, mass-manufactured tools of debatable quality.
A recently found hammer within one of the largest archeological sites displays the oldest known variant of an imprinted Black-capped Hammer. Archeologists and Clerics alike are thrilled, that the insignia is the symbol of Maned himself.
Te legendary smith Theodor Flinkstahl was famous for being so well established and for having so many colored bands for his hammer, he eventually took up a second apprenticeship in a different field, to have a second hammer to place them.