Cut swordfish into 1-inch pieces and in a shallow dish toss with garlic, lemon juice, and oil to coat. Marinate swordfish, covered and chilled, 20 minutes.
In a skillet cook bacon over moderate heat until pale golden but still soft and transfer to paper towels to drain, reserving fat.
Thread swordfish, bacon, and tomatoes onto four 10-inch skewers. Brush kebabs with some of reserved fat and grill on an oiled rack set about 6 inches over glowing coals 3 to 4 minutes. Turn kebabs and grill 3 to 4 minutes more, or until swordfish is just cooked through.
