Hide helmet.
 

Does it not work properly? Or is it just not a kunark function?

It was removed as it is a non classic feature

Not classic man

Not classic, yes - but Kunark or vel? I thought I remember it from around that era..

Get a Tranix or Froglok crown :)

If you double click it fast, it'll hide your helmet. However, its only client side and everyone else will still see it.