This dagger has been endowed with a magical curse which not only causes the user physical HP damage, but also blindness.
The affects of the dagger on the intended target are as of yet unknown.
The dagger was found stuck to the side of the barn in which our heroes were taking respite. It was put there in order to tack to said barn a portrait of one of the heroes. From beginning to end it was to be perceived as a threat and the properties of the knife are certainly no coincidence.