The writer speaks of the teacher who uses his words to instruct people as if the teacher were a shepherd who uses his tools to lead his flock. (See: [[rc://en/ta/man/jit/figs-metaphor]])
This is a simile. Alternate translation: "Wise people encourage people to act, like a sharp stick encourages an animal to move" (See: [[rc://en/ta/man/jit/figs-simile]])
This is a simile. Alternate translation: "Like you can depend on a nail that a person drives firmly into a piece of wood, so you can depend on the words of the masters in collections of their proverbs" (See: [[rc://en/ta/man/jit/figs-simile]])