This is another nifty little detail. One could easily have any _naturally_ occurring holey stone have some power over the supernatural in your world, especially given how powerful these types of beings can be compared to a common person. The same way silver is bane to werewolves, and running water is to vampires, a holey stone helps peel back the veil spirits and their like use to hide from humans.
An interesting idea - it can be made non game specific simply by indicating that the drinkers will be affected by magical rage and leave it at that. Timing, how to resist, etc, can be implemented by whoever uses it.
What this post really needs to improve it is _why_ the lake causes rage? Is there an imprisoned evil god buried in the sediment below the waters? Did 100 berserk demons die in a battle eons ago on the site? Etc. Go to Comment
Certainly a great take of the Dancing Sword idea. This could easily be made rare and not cookie cutter by the need of specific knowledge, as well as for the sacrificing person needing to be exceptionally skilled.
To balance the item, one might note that real Tourniquets must be relaxed regularly to keep the limb from dying. Failure to do so results in the need to amputate the limb. Still, it will save lives at the cost of more surviving cripples.
This item is also easily adapted to Sci Fi by making it a Nanotech device, and being reasonably plausible in my opinion. Go to Comment
There have been some interesting comments here, perhaps some of the best BH conversations I have seen in a while, but I am in agreement with Wulfhere.
Frankly, if the youths attacked, its on them. Treating them with kid gloves feels a bit like imposing modernity. Raiding is not an innocent activity, as you could ask any target the youth party _would_ be able to handle.
And yes, this would cause diplomatic issues, and this seems to be by far the most likely outcome.