Heat the oven to 425°F. Score the skin and fat on each breast without cutting into the meat. Season with 1/2 tsp. salt and 1/4 tsp. pepper.
Heat a 12-inch ovenproof skillet over medium heat. Add the breasts skin side down and cook until the skin is browned and crisp, about 6 minutes. Flip and put the skillet in the oven. Roast until an instant-read thermometer inserted in the center registers 130° to 135°F for medium rare, 8 to 9 minutes.
Transfer the duck to a cutting board. Discard all but 1 Tbs. fat from the skillet. Swirl in the butter and return the skillet to medium heat. Add the shallots and cook, stirring often, until softened, about 2 minutes. Add the wine and simmer until reduced by half, about 2 minutes. Add the broth and simmer until reduced by half, another 2 minutes. Add the peaches, tarragon, honey, 1/4 tsp. salt, and 1/2 tsp. pepper. Stir until the sauce is bubbling, 1 minute.
Slice the duck and serve with the fruit sauce.