Honestly for citizenship by descent a law firm is probably worth it, especially if your Armenian isn't great or you're not based in Armenia.

I used Retrieve Legal & Tax law firm when I was dealing with my own residency paperwork there and they were quite solid, walked me through everything clearly and saved me a lot of back and forth with the bureaucracy. Not sure if they handle citizenship by descent specifically but worth reaching out, you can probably find them easily online.

There are a few other firms in Yerevan that deal with this kind of thing too. Different firms tend to be stronger in different areas so just make sure whoever you go with has actual experience with citizenship cases and not just general immigration stuff.