Hi,
OK.
'Debase' is such a strong verb that it seems a bit odd, almost contradictory, to talk about it in the context of politeness.
Debasing someone commonly involves actions rather than words.
Let's consider a simple scenario like this.
You are an employee who has a manager who is proud and arrogant.
One day you win the lottery and you buy the company.
The next day, you go to work as the owner, and you give him an order.
'"I would like you to go and clean the toilets, please".
He does it, thus showing himself to be debased.
As you can see, the order was politely worded.
Would you consider this to be debasing him politely?
Best wishes, Clive