Catsidhe

I remember the knives and broken glass bit, but the version I had saw her die. Because she had no soul, she was forced to spend an age (can't remember how long offhand) drifting around the world as a spirit, gazing upon children. Each child that was a joy to its parents would reduce the time needed by one year; each child that was a burden, she would weep over, and each tear would add one day.

Ahh, right, I see now...