Place dates in a small bowl. Cover with hot water; soak until softened, 5 to 10 minutes. Reserve 1 tablespoon of the soaking water; drain the dates and set aside.
Pulse ⅓ cup peanuts in a food processor until coarsely chopped, about 8 pulses. Add the drained dates, ¼ cup peanut butter, cocoa and the reserved soaking water; process until dough forms and pulls away from sides, about 30 seconds. Transfer the mixture to a small bowl. Stir in cocoa nibs until evenly distributed. Cover and refrigerate for 15 minutes.
Spoon 1 scant tablespoon date mixture onto a clean working surface; gently press into a 2-inch round (about ⅛-inch thick). Spoon ¼ teaspoon peanut butter in the center of the round. Carefully pinch the date mixture around the peanut butter to seal; roll between your palms to form a smooth ball. Place on a serving plate. Repeat the process with the remaining date mixture and peanut butter. Sprinkle the balls with the remaining 1 tablespoon finely chopped peanuts. Cover and refrigerate until firm, at least 1 hour. For longer storage, transfer to an airtight container and refrigerate for up to 1 week.
