Arrange swordfish steaks in a shallow baking dish, season well with salt and pepper, and coat with 3 tablespoons olive oil. Let marinate at room temperature for up to 1 hour, until ready to grill. (Or marinate longer in the refrigerator, and return fish to room temperature before grilling.)
Heat a grill or grill pan until very hot. Meanwhile, to make pesto, combine olives, garlic, arugula, parsley, oregano, and salt to taste in the bowl of a food processor. With machine on pulse, slowly add remaining 6 tablespoons olive oil. Add 1 1/2 tablespoons hot water, pulsing, until coarsely pureed. Set aside.
Place fish and leeks on grill. Cook for about 5 minutes; remove leeks from grill, then turn fish. Cook fish for another 5 minutes or until nearly cooked through; remove from grill, and transfer to a shallow serving dish.
Arrange leeks on a serving platter, and place fish on top. Spoon pesto over hot fish, turning fish to coat well. Pour juices over fish, and serve.
This recipe appeared in Martha Stewart Living's 10th Anniversary Cookbook without leeks.