Peel, core, and slice the soft pear and place in a saucepan with the vinegar and shallots. Bring to a gentle simmer and continue to cook until the liquid has reduced by half, about 6 to 8 minutes. Set aside to cool briefly, then transfer the pear mixture to a blender and process until smooth along with the honey, Dijon, salt, and pepper. While the motor is still running, drizzle the walnut oil in slowly until the dressing is emulsified. Transfer to a nonreactive bowl , cover, and refrigerate until ready to serve, up to several days in advance.

Quarter and core the firm pears and thinly slice the quarters lengthwise. Add to a mixing bowl toss gently with a small amount of the dressing.  Arrange the pears on 4 serving plates and then add the endive and arugula to the bowl along with the grapes and toss with enough of the dressing to coat. Arrange the arugula-endive-grape mixture on top of the pears and then crumble the blue cheese over all. Garnish with the walnuts and drizzle with more dressing if desired.