- Preheat oven to 450°F.
- Toss together squash, onion, 3 tablespoons of the oil, 1 teaspoon of the salt, and 1/2 teaspoon of the pepper on rimmed baking sheet.
- Roast in preheated oven until squash is browned and tender, 20 to 25, rotating pan on rack after 15 minutes.
- Let stand until cool enough to handle.
- Meanwhile, whisk together vinegar, lemon juice, honey, oregano, remaining 2 tablespoons oil, 1/2 teaspoon salt, and 1/4 teaspoon pepper in a small bowl until thoroughly combined.
- Combine chickpeas, olives, and arugula in a large bowl; drizzle with dressing, and toss to combine.
- Add squash mixture and feta; toss lightly to combine.
- Sprinkle with parsley, and serve immediately.