The Radiant Guard was a shield for the Vanguard class in Nosgoth. It was an alternative to the default Hybrid Tower.
The Radiant Guard was described as a "relic ... looted from an ancient treasure trove" which "celebrates the legendary past when the sun still shone."[NOS]
The alternatives to the Radiant Guard were:
All shield variations, like skins, were vanity items without unique functionality.
The Hybrid Tower is referred to as "VanityItem_ShieldHuman_4" in the Nosgoth game data.