There is something about a dominatrix with a pony tail that makes her appear more severe. Any thoughts on why that seems to be the case?

Not just a pony tail. Any style that has the hair pulled back tightly (think Chignon or French Twist etc.) tightens the skin and accentuates the cheek bones, giving an austere/harsher/more severe look. Combine it with dramatic makeup and form fitting black leather and it's a classic look!

Love this post, and Love that image of a domme.

Of whom do you speak? Anyone in particular that has this image that pushes that button.

Celeste

It is a pretty "classic" look so lots of Dommes over the years. Victoria Rage of Seattle comes to mind in her "hair up" photos.

Can't give you specific examples but some of the Blonde "English Rose" look dommes in the UK often wear their hair like this

Think about Largatha from the Vikings TV series

Probably associations we have with hair being pulled back by people in authority. Loose hair implies a kind of freedom and wildness.

I love a long straight ponytail. I don't have the hair for it myself but I do have an extension I can add to my own which I just love the look of. Classic Dominatrix vibes!