In a small saucepan, bring the broth (or stock) to a boil. Reduce to a gentle simmer at medium-low heat.
In a medium-size, heavy saucepan, heat the olive oil and 2 Tbs. of the butter over medium-high heat. Once the butter melts, add the onion or shallot and cook, stirring constantly, until translucent and softened, 3 to 4 minutes. Add the rice, stirring constantly to coat well, and cook until the outside of the rice is translucent, about 2 minutes. Add 3/4 cup of the duck confit and 2 tsp. of the sage; stir to combine. Immediately raise the heat to high, add the wine, and cook, stirring, until most of the liquid has disappeared, about 2 minutes. Add enough broth to just cover the rice, about 1 cup. As soon as it simmers (which should be almost immediately), reduce the heat to low or medium low to maintain a steady but gentle simmer. Stir frequently and continue to add broth, a scant 1/2 cup at a time, as it’s absorbed by the rice.
After about 15 minutes, begin testing the rice for doneness. By this time, you should have added about 3 cups of the broth, and the rice should be creamy but slightly firm. Once the rice is tender to the bite with just a tiny white grain left in the center of the kernel, stir in the Parmigiano and the remaining 1 Tbs. butter. Season to taste with salt and pepper. Stir constantly until the cheese and butter are fully incorporated. Cook for another 1 minute, until the risotto is creamy but not runny. Remove from the heat. Serve immediately, garnished with the remaining confit and sage and more Parmigiano.