None of the autoparts stores stock the newer pathfinder rear wiper in my area and I'm assuming others have the same problem. I found the wiper and a installation video:
Newest Generation Pathfinder Rear Wiper Blade: https://www.wipers123.com/product_display.php?make=Nissan&makehid=Nissan&year=2008&yearhid=2008&model=Pathfinder&modelhid=Pathfinder
Pathfinder Rear Wiper ( XX-B ) Install Video: https://www.wipers123.com/wiper_blade_installation_videos.php
I was always told not to force mechanical things, but you have to apply a fair amount of force to snap it out. Its much easier once you see it done.
Hope this helps.