Marinate the swordfish in a ziplock bag with oil, garlic, salt, and pepper.
Thread the cubes and lemon slices (fold in quarters) on wooden skewers, alternating so that a folded lemon slice separates each cube.
On a very hot grill, add the skewers and allow to cook for only a few minutes (until it releases from the grill easily) on each side. Be very careful not to overcook.