Ruby Vampir
This limited-run variant of the Spanish Ruby .32 ACP semi-automatic pistol was produced between 1918 and 1932 by a somewhat obscure (and now defunct) Romanian monastic order. The Ruby Vampir differed from the original variant not so much in basic performance as it was a fulfillment of the Ruby’s original promise: Vampirs were machined and manufactured with the highest production values, resulting in a gun that was even more reliable, rugged, and accurate than the original. More to the point, the Vampir was remarkably good at ghoul-killing.
It’s their skulls, you see. Ghoul skulls are extremely tough, to the point where a .44 Magnum round was considered the minimum necessary to reliably penetrate it. .45 ACP can do it, but it takes about three shots. .30-06 bounces off. But, somehow, a .32 round from a Vampir penetrates the average Undead skull six times out of seven. Something about the combination of the gun, the caliber, and the fact that every single Vampir was put together by a team of pious Orthodox monks just made this the go-to gun for clearing a ghoul warren. Or general Undead, for that matter; if bullets can kill it, a Vampir will do the job. The range isn’t great, but that’s what .50 caliber sniper rifles are for.
The bottleneck was always in the production line: the monks made about three thousand or so Vampirs a year, and there was a waiting list for every single one of them. Fortunately, the effect worked with standard .32 ACP, and these guns were extremely well made, so somebody who really needs a Vampir and has the money (lots of it) or influence (ditto) to acquire one usually can. Eventually. And if influence is used to acquire a Ruby Vampir, it’s invariably a loan, not a gift.
Attempts have been made to secularly replicate the production line, but iot really does require the devout efforts of a dedicated Eastern Orthodox monastic order for the effect to work at all. And there is a faction inside the Romanian Orthodox Church giving consideration to setting one up. The need for good ghoul-killing guns has not abated over the years, after all. Quite the contrary.