Taedetium Mines
These remarkably nasty devices – for a given value of nasty – are most often used by groups and individuals who expect a visit from various types of supernatural creatures, entities, people, what have you. Taedetium mines closely resemble the infamous ‘Bouncing Betty’ shrapnel mine; which is fair, because that’s what they were derived from. The mine is set at ground level and connected to a trigger wire or light beam; when triggered, the mine springs into the air and ‘detonates’ at about waist level. Unlike the Bouncing Betty, the shrapnel produced is low velocity: it might penetrate naked flesh, but it’s more likely to get embedded in clothes.
…Which is immaterial, because the shrapnel is made out of Taedetium, which is a complex irrational element that can only survive in our plane of existence by eating magical and/or other supernatural power. It’s highly unstable in terms of its ability to even exist, but for the next five minutes or so any supernatural entity that comes in contact with it is going to have absolutely no esoteric powers at all. Depending on the entity, this can mean anything from a painful loss of power to an instant True Death; the only practical defense against Taedetium’s power-sucking properties is to keep the stuff away from you.
Taedetium, ironically enough, can only be created by an esoteric adept; and as storing the stuff is pointless if not actually impossible, each Taedetium Mine is actually best thought of as a spell that simply needs one final event in order to be completed. This makes them visible to anyone or anything that can scry magic. Disarming one is simple, too: shooting it usually disrupts the spell.
One last note: Taedetium Mines are cordially hated by all supernaturally-inclined groups and individuals, but the weapons are far too useful to making banning them practical. Everybody would simply cheat. However: use a Taedetium Mine on somebody vulnerable to it, and you’ve effectively given that person permission to uncrate the really nasty abilities in response. And nobody in the esoteric world is going to raise too much of a stink over that. In other words: cave magum, as the apprentices might say…