Whisk together the pomegranate juice, vinegars, salt and pepper. Add olive oil and whisk again. Re-whisk when ready to use.
Preheat oven to 425° F
Melt 2 tablespoons butter in a large non-stick skillet over medium-high heat. Add as many wedges as you can, you may have to do this twice, to not overcrowd the skillet. Cook until brown on each side, 5 minutes. Transfer squash wedges to a rimmed baking sheet, season with salt and pepper. Place in the hot oven and bake for 20 minutes.
Mix arugula, pomegranate seed and pine nuts in a large bowl. Drizzle half of the dressing. Divide among plates, top with squash and some more dressing.