Get a second controller.

Turn on the controller.

Press start on the second controller and start co-op. DO NOT PICK A SECOND GAMER PROFILE OR ANOTHER CHARACTER! JUST PRESS ACCEPT!

Discard all abilities for henchman, which should be exactly the same as your own.
End co-op by quitting with henchman. All experience will go to the main character.

Send your newly glitched experience.

As you can see, this glitch works better when you are stronger, as you will get more experience back. Do this several times and you will have max stats fast(ish).