Also Romansh: Source: "Vornamen in der Schweiz. Prénoms en Suisse. I nomi in Svizzera. Prenoms in Svizra" (1993) published by the Association of Swiss registrars https://sursassiala.ch/2015/01/15/familienforschung/
Lovely name and should be pronounced correctly, Cash-en. I'm annoyed by the few movies that have come out lately with characters named Cassian pronounced Cass-ee-en.
KASH-ən reminds me too much of "cash an' carry," but I'm glad Cassian isn't pronounced like KAS-ee-ən. It sounds more masculine with the proper KASH-ən pronunciation.