In a non-reactive container (glass or stainless steel) with a fitted lid, whisk the vinegar, wine, sugar, bay leaves, peppercorns and pepper flakes together. Add the pear slices, toss gently to coat, cover and refrigerate at least 12 hours, or until ready to use.
Remove the pears from the pickling liquid and strain, reserving any liquid. Place 6 cups pears and 1-1/2 cups strained pickling liquid in a food processor with the mustard and puree until smooth. With the motor running, slowly add the oil in a steady stream, continuing to process until the ingredients are fully incorporated and smooth. Season to taste with salt and pepper, cover and refrigerate until ready to use.
To serve, combine 2 tablespoons dressing for each cup of arugula and toss gently to coat. Place 1 cup dressed arugula on each of 24 chilled salad plates. Top each salad with 2 pickled pear slices, 4 slices cucumber, 1/4 cup shredded carrots, 4 blackberries, and 3 tablespoons crumbled feta cheese. Serve with extra dressing on the side.