The Unhealing Wound
PeCo
R: touch D: Mom T: Part
The wound touched loses its capacity to heal. The flesh and bone within an inch of the damage cannot knit back together where it is separated nor grow scar tissue. Blood can clot and scab because it comes from elsewhere in the body but the scabs are easily knocked off if they adhere at all, to reveal raw and bleeding meat.
Guideline ???
Problem is, there's no ongoing effect to end when the wielder dies. Could be treated with ritual CrCo, sufficient debridement - which could be crippling in it's own right - or a sufficiently long lasting non-ritual effect that grants a magical capacity to heal - but would leave a section of flesh vulnerable to non-healing wounds in the future when it ends.
Okay, maybe I'm telling something stupid, since more knowledgeable people than me have answered already, but, disregarding the "until the wielder dies" part:
Give the Sword a PeCo wound spell, touch range, duration sun, constant effect, unlimited uses
Thus, the wounds last until the sword is destroyed.
Here's a thought... would there be a way to have all the constant effect wounds of the item "reset" when a new owner claimed the sword. I'm just thinking, since there is a mystical property to ownership (as evidenced by the fact that it engenders an arcane connection), perhaps part of the effect trigger for the items powers is that the constant effects will stop being "renewed" when the new owner takes possession of it.
Where it's a MacGuffin type item you can one option would be to make any weird nonstandard effects the result of experimentation. The maker was trying for a standard PeCo effect but after a fistful of dice rolled where rolled they got an enhanced modified effect. Non standard duration and/or activation explainable but not easily repeatable.
No perdo isn't really forever. Things that are destroyed don't spontaneously come back into being (unless you have the appropriate flaw) but the magic doesn't make them stay destroyed forever. You can't make a permanent invisibility spell, a perdo terram hole in the ground only stays unfillable for the duration of the spell. If it's the nature of the target to recover then it will recover after the spell expires.
There might be some way of moving up a step and damaging the body's ability to heal itself rather than causing a wound but I don't think that this would get you an "infinite loop" setup where the body's ability to heal itself can't recover because the body's ability to heal itself has been destroyed by a perdo spell (at least not in my game).
I suppose it depends on the unnaturalness of the flesh after the spell. Solid matter without weight is so unnatural that the quality is regained as soon as the spell ends - it is part of the essential nature of solid matter to fall. Is the ability of living flesh to heal such an essential quality that it cannot lack it without ongoing magic?
Well, the body does not necessarily heal from all diseases -- think of Leprosy. I think it would be reasonable to concoct a variant disease that is localized, and that does not heal. The disease affects an open wound, and prevents it from healing, very much like some infections.
