I’m still trying to find out about Armenian catenas and biblical commentaries.
It seems that there are not many references to books in Armenian on the net. Apparently the Mesrop Mashtots Matenadaran, the Institute of Old Manuscripts, Yerevan (not the same as the Armenian National Library) has a new website. Unfortunately it is only in Armenian now. But you may see there many beautiful miniatures. One can search on that site in the bibliographies too, to find what is there in the Matenadaran collection (although presumably only if you know Armenian and can type Armenian text).
There is also a website of publications by the Gandzasar Theological Centre where my contact works and the Publishing House of Holy Etchmiadzin. She adds:
I’m still adding annotations in that section of the website and there are still many books that need to be added there. I think I’ll put there also that bibliography of biblical commentaries when I get it. So you’ll have more references for published Armenian texts. You may check our website from time to time to see the additions. http://www.vem.am/en/topics/books-1/
The bibliography of biblical commentaries and catenas in Armenian is something we should all be interested in, and I will add more details as I find out more.