As far as I know, they don't regulate Personal Items like Purses.
I know several flight attendants that work for a major airline. When they are in training they will get recommendations on what suitcases and personal items they have found to work best over the years and as a result, almost all the flight attendants wind up using the recommended suitcase and purse, etc. The "Purse" is just a bag that carries their lunch and personal items like car keys, cell phone, and makeup. You will usually see it riding on top of the roller suitcase which thee need for the layover at the end of the day, they always bring that suitcase as they may get redirected mid-shift to a different flight with a layover that was not planned when they went to work that morning.