Answer: It reveals Ahab’s commitment to his mission for revenge.
In this passage, the speaker is describing the impact that Ahab caused when meeting him for the first time. He describes his white, whalebone leg, and how he fashioned it out of a sperm whale's jaw. He also describes how there was an auger hole on the deck, upon which Ahab would steady his leg. He would stand there and look out beyond the prow for hours on end. The speaker also describes his attitude of determination and wilfullness. All of these elements contribute to showing how commited Ahab was to his mission.