This smelly, filthy garment must be made out of some special fabric in order to have withstood the foulness of the bridgekeeper's body. Oddly enough, it has plasma burns and scorch marks all over it, as if these weapons were used against it... to no effect. You have NO idea why it's purple.
”— in-game description, Fallout 2
The Bridgekeeper's robes is an armor in Fallout 2.
As one would note it has the exact level of protection as a combat armor but with half the weight and no bonus to Radiation resistance, making it perfect to use before getting a power armor and later by one of your companions.