Mechanical / Maths sort of question.

[Piemaster]

Marine engineers guide to torque:
bolt sheared = too tight
bolt not sheared = slack

 

[TheDoctor]

Get a normal wrench and get fit. You dont need any of this torque setting stuff unless you are fitting car wheel nuts.

That's so much bollocks I don't know where to start.
I think you're confusing an air driver with a torque wrench, although you don't appear to know anything about either...

To answer the OP, arranging levers and weights is exactly the way to check a torque wrench. You're going back to first principles and the fundamental quantities - weight and distance.
5 pound weight and 2 foot distance will be 10 foot pounds. It couldn't be anything else.