Heat grill to high. Whisk together juices, oil, and chili powders in a medium baking dish. Add the halibut and turn to coat. Marinate for 5 minutes.
Remove the banana leaves from the water and shake off excess water. Place the leaves on a flat surface. Remove the halibut from the marinade, season with salt and pepper, and place 1 fillet in the center of each leaf. Wrap the banana leaf loosely around each fillet. Place the packets flat on the grill, close the cover, and cook for 8 to 10 minutes or until just cooked through. Carefully remove from the grill and serve the fish in the banana leaf, if desired. Serve fish with the Orange-Pineapple Relish.
Whisk together the lime juice, orange juice, chile de arbol, honey, and oil in a medium bowl. Add the remaining ingredients and stir to combine. Season with salt and pepper, to taste. Let sit at room temperature for at least 30 minutes before serving.