Headcanon: Peter was short-tempered often. Because of his strong passion, he had the tendency to lash out in situations. Edmund was also short tempered, but he hid it well. He was extremely cool headed, which contrasts nicely to Peter. While Edmund handled the diplomatic and political side of things, Peter gathered troops, took care of his people, and gathered great loyalty with his compassion.
“To the glistering eastern sea, I give you Queen Lucy the Valiant. To the great western woods, King Edmund the Just. To the radiant southern sun, Queen Susan the Gentle. And to the clear northern skies, I give you King Peter the Magnificent. Once a king or queen of Narnia, alway a king or queen of Narnia. May your wisdom grace us until the stars rain down from the heavens.”