Such a bloodied claymore has history way back through lines of father and son. In fact only one place near the handle still holds a metal tone, because of a magical barrier, and it has ingraved in it words that forever speak out to the swords bearer. Those words, like a guilty memory, can never be forgot.
“Thou who shall kill a sons father, shall then be killed by a fathers son.”
You receive a vision of a rooftop "somewhere close by", where a rare moss grows; in the vision, you know the moss is suitable for greatly enhancing the effects of certain types of potions. Now go and find that rooftop. Don't fall off. (Of course, rooftop runners *will* be taken for miscreants by the local City Watch....)