The Glow of Aknar is a golden medallion that the king of Aknar wears instead of the traditional crown. Folderol explains that crowns are a dime a dozen among kings and that the Nablobs like to be different.
The medallion glows when there is a king enthroned in Aknar but stops glowing when a new king needs to be found. The new king has to be a Nablob and if the medallion is given to the wrong Nablob or the right Nablob refuses the medallion then Aknar will be without a king for another three hundred years.
The medallion seems to protect Aknar with sorcery as when it no longer glows the kingdom is weak and prone to attack but when it is glowing the rightful owner seems to be able to repel threats, as both shadow demon and Venger do not challenge Folderol when he is wearing the Glow of Aknar.