In an oven-proof skillet, heat the oil and saute the crab legs with the ginger, jerk spice, and rosemary. Cut the lime in half and squeeze the juice. Add the lime juice to the skillet. Add the water and toss to coat the crab.
Put in the oven and cook for 4 to 5 minutes until the crab heats through and is flavored with the spices and herbs. Add the butter and toss with parsley and celery leaves. Season with salt and pepper and serve.