Removing the skins from fresh-shelled favas is a necessary task that's worth the effort. The prepared beans have a firm texture and a nutty flavor.
Cook beans in boiling water 1 minute; drain. Plunge beans into ice water; drain. Remove tough outer skins from beans; discard skins. Place beans in a large bowl; set aside.
Thread shrimp evenly onto 6 (12-inch) skewers; brush with 1 teaspoon oil. Sprinkle shrimp evenly with 1/4 teaspoon salt and 1/8 teaspoon pepper. Place skewers on a grill rack coated with cooking spray; grill 1 1/2 minutes on each side or until shrimp are done. Cool slightly; remove shrimp from skewers. Add shrimp to beans.
Combine remaining 5 teaspoons oil, remaining 1/4 teaspoon salt, remaining 1/8 teaspoon pepper, juice, and garlic in a small bowl, stirring with a whisk. Drizzle juice mixture over shrimp mixture; toss to coat. Stir in parsley.
Place 1 radicchio leaf on each of 4 salad plates; spoon 1 cup shrimp mixture into each leaf.