I purchased a standard wiper arm replacement (like you'd use as a replacement for main windshield on the Malibu Maxx)
You can purchase at any big box retailer, I recommend you buy one that has the metal inserts that show on both sides of the rubber blade. Length of blade doesn't matter since we will cut it to size.
Remove the rubber blade from the new assembly and cut the rubber blade to your replacement length (14" in this case) and (after removing the old blade from the wiper blade on the car by sliding it off) slide the new blade on to the old assembly.
The rubber blades that incorporate the metal inserts will hold better on the old assembly.