Melchizedek influences Santiago's actions primarily by helping him recognize important signs and omens that he might have overlooked and by encouraging him to not give up on his journey toward discovering his Personal Legend. Melchizedek's guidance instills in Santiago the understanding that the universe conspires to help those who pursue their dreams, which propels Santiago to take decisive action toward his goals.
While he does not provide direct answers or reveal the location of the treasure, Melchizedek emphasizes the importance of following one's heart and remaining open to the signs along the way. This encouragement is crucial for Santiago as he navigates the challenges of his quest, reinforcing the idea that perseverance and attentiveness to one's surroundings are vital in realizing one's destiny.