Knives and firearms leave traces of blood. Bombs shake whole buildings and streets. Poisons can always be detected.
But a destructive word can provoke Evil without leaving behind it a single clue. Children are subject to years of conditioning by their parents, artists are mercilessly pilloried, women are systematically undermined by remarks made by their husbands, the faithful are kept apart from religion by those who judge themselves capable of interpreting the voice of God.
Check to see if you yourself are using this weapon. Check to see if someone is using this weapon on you. And put a stop to both.