Simmer the Port in a small saucepan until reduced to 2 tablespoons. Let cool, then whisk in the red wine vinegar, shallot, salt and pepper, to taste. Gradually whisk in the olive oil.
In a large bowl, toss the frisee, radicchio, and pear. Divide the salad among 4 plates. Drizzle with the dressing; you probably won't use it all. Using the medium holes of a box grater, shave the blue cheese in a fine snow-like shower over the salads. Scatter the walnuts on top and serve immediately.