The fragrant brushing of spices called for here will add a piquant flavor redolent of Indian cooking to fish steaks, whether swordfish or halibut. Mix together all ingredients except fish and margarine. Spread mixture evenly on both sides of fish. Place fish in shallow glass or plastic dish. Cover and refrigerate at least 12 hours. Set oven control to broil or 550F. Arrange fish on rack in broiler pan and drizzle with melted margarine. Broil with tops about 4 inches from heat until light brown, about 7 minutes. Turn. Drizzle with melted margarine. Broil until fish flakes easily with fork, 5 to 7 minutes longer. Note: Garam masala is a blend of ground spices with many variations. It is available in Indian markets and at some supermarkets.