Here the hand represents the fool's responsibility to deliver the message. Alternate translation: "Whoever sends a fool to deliver a message" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Cutting off one's own feet is an exaggeration for harming one's self. Alternate translation: "harms himself like a person who cuts off his own feet and drinks violence" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-hyperbole]])
Violence is spoken of as if it were a poisonous liquid that someone might drink. Alternate translation: "harms himself by being violent" (See: [[rc://en/ta/man/translate/figs-metaphor]])