Sardonic and secretive, ----> Sardonic as in sarcastic, which elsa is. Secretive about her past.
Vitreous and pristine, ---> "glass like snowflake" marking from profile, pristine as is in her profile
Held up in your ivory tower, ---> these are markings and personalities, which are carried by her white body
Absconding, then hiding from the world. ---> stole the armor and has basically been avoiding the basin