Fry the bacon in a large skillet over medium heat until crisp, about 8 minutes.
Meanwhile, in a large bowl, combine the arugula, dates, almonds, and Parmesan; set aside.
Transfer the bacon to a paper towel-lined plate. Carefully pour 2 tablespoons of the warm drippings into a small bowl. Add the vinegar, mustard, salt, pepper, and oil and whisk until combined. Drizzle the warm vinaigrette over the salad and toss. Divide among plates and top with the bacon, crumbling it if desired.