The metal windshield wiper arms that hold the wipers are spring loaded so that they keep your wipers pressed to the windshield in a storm. Unfortunately this means that without the soft wiper on the end, that metal arm can do some serious damage to your windshield!
Prevent the wiper arm from snapping back and hitting your windshield by carefully resting it against the windshield while you are getting your new wiper ready to install. Even if you just turn around to grab it, play it safe and "park" the arm in the down position.
*Park the wiper blade against the windshield to keep it from snapping back.