I couldn't get the darn thing off. It would not slide off and I couldn't stand to try anymore because it was like a -10 windchill and my habds were frozen. Any tips?

I wanna say there is a like C-clip or something holding it. Get that off them it should pull right off.

The rear wiper is held on by shear pressure.

Getting it off can be tricky.
IF you have a WIDE flat screwdriver.

Stand behind your XJ, screwdriver in left hand.
Place blade between edge of wiper arm and "big nut" at base of wiper pivot.
Twist screwdriver while grasping the arm with your right hand.

A few attempts and it sould POP off in your hands.

where it hooks to the motor arm there is a tiny little piece of metal, mine just pulls out but most of them you pull away from the motor shaft and then do what howler said, use a screw driver, i used a thick prybar cause i dont have that big of a screwdriver.

My hands were so frozen I couldn't type.

Were you referring to the blade or the arm?

The directions I gave were for the entire arm.

Blade removal requires you place screwdriver in the little gap between the blade and arm.
Give a slight twist and the blade should pop off the arm.

I have no idea how to remove the rear wiper blade.
This is too complicated for words to explain this.
Is there a video for this?

Rear wiper is the same style as the front. Easiest way is to turn the wiper perpendicular to the wiper arm, hold the little latch on the underside (if it's still on there), and give the wiper blade some love taps with the palm of your hand to slide it up the wiper arm.

There is no tab to press like the front wipers.
It might even be rusted solid. I think it's original, just like most everything else on this XJ.
Here are 4 pictures, in various degrees of turning. (0, 45, 90, 175)
The last one is almost fully inverted 175 degrees.

Haha yeah that looks about right, mine looked the same when I bought the XJ. Turn it 90 degrees and just bat at it with your hand near the middle. They usually break free in two or three good blows. It doesn't look like you have a very good place to pry with a screwdriver on that particular blade.