Sartorial is something relating to tailoring or clothing. An example sentence would be: She always wanted to take a sartorial class of some sort.

She was known for her impeccable sartorial taste, always dressed in the latest designer fashions.

of or pertaining to clothing or style or manner of dress

A despot is an absolute ruler. "Sartorial" has to do with clothes. I don't know where you saw the phrase, but mentally replace it with "fashion Nazi" and you should be able to get the overall idea of the sentence right.

Tailors