Combine the Armagnac, maple syrup, cranberry syrup, thyme, coriander, and pepper. Marinate the foie gras scallops for 6 to 8 hours in the refrigerator. Remove the foie gras from the marinade and reserve marinade.
In a very hot saute pan, pan-fry foie gras for approximately 1 minute each side until golden brown. Salt lightly and place on a serving platter. Cover with plastic wrap. Refrigerate. Remove from refrigerator 20 minutes before serving to bring to room temperature.
In a saute pan over medium-high heat, add the butter and melt. Add the shallots and saute until translucent, about 2 minutes. Deglaze with white wine and cook until the liquid is reduced by half. Add the duck broth and reduce by 1/3. Add the reserved marinade, maple syrup, and fresh cranberries. Reduce until mixture thickens and then puree until velvety smooth. Add the lemon juice and salt and pepper, to taste.
Pour sauce over foie gras scallops and serve.