Preheat your grill to medium-high. Place the first 6 ingredients in a medium-sized pot and bring to a simmer. Simmer the sauce, stirring regularly until it thickens, about 2 to 3 minutes. Stir in the blueberries, salt and pepper. Reduce the heat to low, cover and reserve until the fish is cooked.
Pat the halibut dry with paper towel. Brush with the olive oil and season with salt and pepper. Lightly oil the bars of the grill. Grill the halibut 3 to 4 minutes per side, or until just cooked through. Plate the fish, top with the sauce and serve.