The setting and technology level is late Medieval to early Renaissance. I have a character who possess the ability to create and manipulate flames, however, the power comes with a single drawback - notably, said character requires fuel in order to sustain the flames for any given length of time. Once created and sustained, he also possesses minor pyrokinetic abilities, i.e. he can direct the flames in ways that he wants, although it's not to the point of creating massive walls of fire or anything of that nature.
Given these limitations, I decided that the best weapon for such a character would be an oil-throwing gun. As in, kind of like a water gun, except instead of shooting out a thin jet of water, it fires a thin jet of oil, whereupon said character lights the oil on fire and uses his pyrokinesis to assist the now-firebolt into flying further.
- Must be something consistent with the tech level - both materials, and techniques involved in the creation of said weapon.
- Nothing explosive involved, i.e. gunpowder - the idea is to make this only dangerous in the hands of a trained professional with magical powers. I don't know how you'd involve gunpowder, but I'm just covering all my bases.
- Oil isn't the required liquid to be fired from the chamber, however given that it's easy to acquire in bulk (well, relatively easy) and the fact that it's highly combustible when released in a spray, it seemed like an ideal choice. If you have a better liquid, go ahead and use it.
- Given that the character wielding the crossbow has pyrokinetic power, range isn't much of an issue - I don't need it able to shoot the jet of oil a hundred feet, but it should be able to at least do ten. Furthermore, the amount of oil isn't important either, because magic can make it burn hotter than it should, though, again, the more oil the better.
- For purely external reasons, and not because I expect it to be practical, some part of the mechanism must involve the crossbow's arms, additionally, it must look like a standard crossbow. It doesn't matter how, just that it does. (The Watsonian explanation is that it's so it can be disguised as a normal crossbow.)
Lastly, the more technical, the better! If you can give me an estimate of range or even give me diagram of how it might work, that would be appreciated.