Going back to the German legends, the source of a werewolf’s power is something known as a wolf strap. This is a magickal device in the form of a belt or something similar that when worn turns a person into a wolf.
According to the old German legends a wolf strap could be gotten by making a deal with the devil. However some werewolves did get their wolf strap through inheritance (supposedly from a relative that had made the deal).
Typically a person would transform into a wolf in order to 1. Steal livestock 2. Rape 3. Kill people they had a grudge against. In any case, these were not things being used for good purposes.
There were some other facts about the wolf strap that show up from time to time that are important to consider. First it was said that it could never be lost nor gotten rid of once a person had made their deal. Secondly it could only truly be destroyed via a specific holy ritual performed by the church.
It’s also interesting to note that, based on folklore and supposed accounts, some later theologians had come to the conclusion that the individual was not actually shape shifting, but rather being knocked unconscious while a demon rampaged around and later waking up with the demon’s memories.
Back to the point though, the wolf strap, and how exactly it works. Now I’ve never seen a working wolf strap, so this is largely speculation. But I have seen similar things and can guess how this must work based on how they work, and some of this information is channeled (for what that’s worth anyways).
I don’t believe in the Christian god nor do I believe in his adversary, so I’m going to through out the devil making deals theory right off. However there are lots of things out there that can easily fit into the Christian definition of a demon, and no doubt a devote Christian would label a horrific, yucky, monster as a demon. So I will buy the deal part.
But how does it work, and what does the demon, or whatever it is, get out of it? It’s a possession. The person looses control of their body at which point the entity itself takes over while being able to transform the physical shape of the body. I’ve heard of possessions where the possessed is able to change some physical aspects of themselves, however nothing to the extent of turning into an animal. But it would theoretically be possible, and much easier than manifesting form from nothing.
The wolf strap itself is possessed with the entity. This entity is able to jump into bodies via the wolf strap when it is worn. Because of the entity, the wolf strap itself would be sentient. This would give it some ability to at least influence those around it, and a sentient object can find its way back to a person (aka can’t be lost). A non-sentient object can even find its way to a specific person if it’s properly enchanted to do so.
As for destroying the wolf strap, it would be destructible, but that wouldn’t be the best way to go about it. Destroying the wolf strap could let loose the entity inside of it. At least inside the strap it’s somewhat contained and you know where it is. Unleashed there’s no telling what it could do. Even if it chooses just to go into another strap, you don’t know where that strap will turn up, when you had the entity trapped in one prior to destroying it.
Without seeing the ritual involved with destroying the wolf strap I can’t tell exactly what it was meant to do. One solution would be to call forth angels to deal with the entity once it’s released. Another would be to seal it out of this dimension or send it to one that it can’t easily escape from. Or it could have been a bastardized pre-christian ritual that no longer worked properly because important parts were removed (such as asking a specific deity to take care of the entity). Unfortunately I haven’t seen a copy of one of these rituals.