Chisel

The standard stone mason's chisel is a humble instrument, and is often put to use in benign ways, shaping and carving stone. Unfortunately, it is also a symbol of tyranny and cruelty.
Deep cover agents of the Vanorax Empire use the chisel as a symbol of inevitability and domination. It is also occasionally used as a symbolic weapon of execution, with the chisel hammered into a prisoner who has been exceptionally defiant to the empire. This is typically reserved for outside threats and is used to send a message.

Significance

Deep-cover agents of the Vanorax often use a chisel to signify their loyalty to the empire. The idea behind the chisel as a symbol is that it represents an implement that can chip away at even the strongest barriers over time. To the Vanorax, a chisel means that even the stone fortresses of the dwarves will eventually fall to ruin if enough persistence is applied, but it actually has an even more sinister second meaning for those especially in the know.
Dwarves are not the only ones who use stone as a symbol. Stone, especially worked stone, and statuary in particular is a symbol of the Eternal Citadel and the Preservers who serve it. They have been especially tireless opposers of the tyranny of The Wyrm Empress. It is them that the chisel is ultimately meant to represent the downfall of, because there is no citadel anywhere that the Wyrm Empress wants torn down more than that one.
Vanorax agents typically do not carry the chisel on their person, but rather will leave one lying around in their surroundings, a simple, innocuous item that doesn't seem particularly threatening on its own. To some craftsmen in the know of this symbolism, this means that chisels are only brought out long enough to actually use them and are then quickly put away.