I would expect the effects of a strap or tawse on the bottom to be similar in perception and severity to the slipper.
I would think the cane stings a lot more than either on the bottom.
At school, I feared getting the cane on my hands (with good reason), and think the tawse on the hands must be of similar agonising intensity (I have talked to several Scots who got it).
After all, (like most women) I am absolutely certain the surface area of my hands (or any other conceivable physical object on bad days!) is in all circumstances somewhat less than that of my bottom.
So the same force applied must be intensified, while in some ways hands are also more sensitive.