In a blender, add 2 cups chopped watermelon, lime juice, honey, garlic, 2 tablespoons olive oil and pepper. Puree until smooth. Pour into a zip-top bag with chicken breasts and let marinate at least two hours.
When ready to assemble salad, take chicken out of the fridge. Remove chicken from marinade, reserving marinade. Bring marinade to a boil in a small saucepan and boil until slightly reduced, or about 15-20 minutes.
Meanwhile, cook chicken under broiler, on grill, or in a grill pan. It should take about 15-20 minutes depending on how hot your broiler/grill is. The last few minutes, baste often with the sauce/marinade. Cook until chicken is cooked through. Let cool slightly before slicing into thin strips.
While the chicken is cooking, cook pasta according to package directions, drain, transfer to a large bowl and drizzle with 1 tablespoon olive oil. Let cool (stick in fridge if need be).
Combine pasta, watermelon, chicken, feta, and cucumber in pasta bowl. Drizzle with remaining olive oil (3 tablespoons) and the balsamic vinegar. Stir to combine all ingredients. Taste and add more oil/balsamic/salt/pepper as you see fit.