Heat the grill to hot. Sprinkle the swordfish steaks on both sides with salt and pepper. Layer 5 grape leaves so they’re overlapping. Place a steak in the center of the leaves. Squeeze the juice of one lemon wedge over each steak. Roll up the leaves over the short ends of the steak, and then roll up one side of the leaves over long end of the steak. Flip the steak over lengthwise and wrap tightly with the remaining overlapping leaves. Repeat with the second steak. Grape leaves will keep the steak moist and add smoky flavor.
Brush the leaves lightly with olive oil. Place the wrapped swordfish on a hot grill, cooking about 4 to 5 minutes per side, being careful not to overcook.
Remove the swordfish from the grill and let rest 2 to 3 minutes, with the grape leaf wrapper still around the steaks. Grill the lemon quarters until lightly charred. Unwrap the grape leaves carefully and plate the swordfish. Drizzle with olive oil and sprinkle with sumac. Garnish with grilled lemon quarters.