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.”
Poison can only ever be the tool of a murderer - as such, alchemists are tightly regulated by the Crown, and anyone found in posession of an unknown substance is forced to taste it themselves.