Put the lemon juice and vinegar in a non-reactive bowl with the fennel and allow to sit 30 minutes, stirring occasionally. After 30 minutes, drain the fennel, reserving the liquid for the vinaigrette. Return the drained fennel to the same non-reactive container along with the drained pears. Cover and refrigerate until ready to use.
To make the dressing, add the reserved liquid from the fennel and the maple syrup to the jar of a blender and pulse to combine. Slowly drizzle in the olive oil, in a steady stream with the blender running. Stir the caraway seeds, salt and pepper in by hand, and refrigerate until ready to use.
To assemble the salad, toss the dill weed and arugula in with the fennel and pears. Drizzle with the vinaigrette and gently toss the ingredients to thoroughly coat and combine. Serve immediately.