In a small bowl, combine the white balsamic vinegar, Dijon mustard, honey, kosher salt, and pepper. Whisk together until the honey is dissolved. Slowly add the light olive oil, whisking constantly. Keep whisking until the dressing comes together and is fully emulsified.
Cut off the stalks of the fennel bulb. Use a mandolin slicer to thinly shave the fennel. Pit and halve the cherries. If needed, toast the hazelnuts according to the directions above. Chop the toasted hazelnuts and crumble the feta cheese.
In a serving bowl, combine the fennel and arugula. Add half the dressing and toss to coat evenly. Top with the cherries, hazelnuts, and feta cheese. Drizzle with more of the vinaigrette, tossing lightly to mix the salad. Enjoy!