Answer:
The figurative language in the underlined sentence builds a tense mood by creating a visual image and showing how easily the barber could hurt the captain.
Step-by-step explanation:
The figurative language creates a visual image of the razor blade against the captain's skin, and the barber's hand on the razor. This image is tense because it shows how close the barber is to harming the captain. The language also shows how easily the barber could hurt the captain, by saying that the razor is the best one the barber has and that it cannot fail. This makes the reader feel the tension between the captain and the barber.