Assumed tech level may be black powder, but I want to do something a little different. Why? I have an idea that is more aligned with the setting, more aligned with the play experience in “Dishonored,” and I think easier to use with the Blades in the Dark mechanics.
An History of Plasm
Electroplasm, in its natural state, is super-gaseous. It is so sparse that it is beyond the dispersion of a gas. The concentration of life, and also of death, that characterizes an urban environment tends to concentrate it. Given time and ever-sifting sources of the weird energy, it builds up to dangerous levels over time, so a single death can manifest an electroplasmic echo known as a ghost.
Another way electroplasm can be rendered dangerous was discovered by Vilantia, a scholar working almost a century ago. He devised a method to distill electroplasm down to a plastic, almost a solid. The process was impractical until his student and successor, Kalmach, connected the process to the electroplasm manipulated by Bellweather Crematorium, and the Spirit Wardens that managed the facility.
Using their abundance (indeed, excess) of electroplasm combined with the distillation process, they created industrial levels of a material known as plasm. Subjected to a sharp shock, plasm reverts through its stages very quickly, instantly moving through liquid to gaseous and then rapidly dissipating. This process releases tremendous energy from the concentrate.
The military and bluecoats and aristocracy all expressed great interest in this new technology. At first single shot weapons, then later more sophisticated weapons emerged.
While many private individuals still have single-shot pistols, military pistols have a double chamber so two bullets may be loaded at a time. More complex models can have up to six in a cylinder, though the preferred design has a port and cartridge system with four rounds. Some weapons are single action, a rare few are double action, none are automatic.
Rifles tend to use a cartridge system with four rounds and bolt action. Older models have a single shot with a breech reload.
Bullets are made of iron, which splinters in a satisfying way with a hit and also disrupts supernatural energy. The propulsion plasm gives a missile a chance to discomfit an incorporeal spirit, or punch a hole in a supernaturally resistant target.
Experience of Use
The finished shell has a ring of glowing blue behind the bullet. They only glow when they are in close proximity to living things, otherwise they fade to black. They are always cool to the touch, or bitingly cold in the chill.
When they fire, the bullets’ plume of mist is chill. It tightens the skin of all those it touches. The sound is glaringly loud as well, as the energy unpacks itself faster than the air can absorb it. Those inhaling the mist or feeling it in their nostrils find it tastes of blood.
Use of plasm is restricted to the military, the bluecoats, rail jacks, and licensed aristocracy. However, plenty of time has passed, and the secret of making it has drifted through the fetid pools of the underworld. For a price, any rogue can find a supplier of plasm weaponry.
There are many ways to gain illegal electroplasm (not least of which is ritual sacrifice.) There are also a number of methods of distillation, each more unpleasant than the last. However, in spite of numerous bluecoat raids and ongoing investigations into sources for illegal plasm, the trade bustles nicely. Especially now that the war is over, and the city has welcomed back its veterans, who are accustomed to having plasm weapons for self defense.