The weapon that killed someone is an anomaly. The place where the slaughter took place has power and contagion. Prayers are intoned and flowers placed at the site of an accident. Candles are lit for the dead. Churches are filled with perfume.
Holy water is sprinkled.
Cathedrals are filled with light and music. Ointment is rubbed into the sword as well as the wound it caused. A rationale lies behind all such actions. A pervasive and profound notion of resonance abounds in the magical worldview and lies at the heart of this whole matter of contagion. Write it all off as superstitious nonsense if you like, but this sense of resonance touches everything, interconnecting them in an unseen web of links between events, people, places, concepts, objects, practices.