In this poem, the word "equipment" is itself a metaphor, a form of figurative language. When Guest says, "With this equipment they all began," referring to "the greatest of men," he means that everyone, even those who go on to achieve great success, start with the same potential. Therefore, equipment is a metaphor for the potential to achieve that equality among all people. Similarly, when Guest writes that the person he is addressing has "Two arms, two hands, two legs, two eyes / And a brain to use," these body parts are also metaphorical. They stand for the way in which everyone has the same potential in life because people all start with the same tools.
In the second stanza, when Guest writes, "They take their food from a common plate, / And similar knives and forks they use, / With similar laces they tie their shoes," he is also referring to the sameness of people's potential. The "common plate" is a metaphor for the commonality of people's experiences, as are "similar knives and forks" and "similar laces." In other words, not only do people start with the same equipment, they also face similar situations as they go through life.
Later, Guest writes that people are their own worst enemies and get in the way of their success. He says, "You are the handicap you must face." In this line, "handicap" is a metaphor for the ways in which people put obstacles in their own paths.