Mid 19th century; earliest use found in The Reliquary; a depository for precious relics. Apparently from classical Latin reliquus + -arian, after reliquary.
Definition of reliquarian in US English:
reliquarian
adjectiveˌrɛlɪˈkwɛːrɪən
rare
Of or relating to a relic or relics.
Origin
Mid 19th century; earliest use found in The Reliquary; a depository for precious relics. Apparently from classical Latin reliquus + -arian, after reliquary.