This is hard. This is
very, very, very hard. Ever since Roman times Armenia has been smack dab in the middle between huge and powerful empires that regularly run roughshod over its territories.
Recently I've been playing a Civilization IV mod, Rhye's and Fall: Sword of Islam, that simulates the medieval Middle East. One of the playable nations is Armenia, and let me tell you, over the course of the game Armenia gets invaded so many times it's horrifying. Starting from 861 AD, there are generic Muslim barbarian invaders, Seljuk horse archer invasions in the 1060s, a declaration of war from the Iranian Seljuk empire, a huge Mongol horse archer invasion in the 1230s, probable declarations of war from the Abbasids, Zengids, Ak Koyunlu, and if you take Azerbaijan at any point the Safavids show up in 1501 and immediately take them.
In other words everyone hates Armenia
On a serious note, one possibility that occurred to me is a personal union between Armenian kingdoms and Georgian ones to create a stronger Caucasus; the historical biggest weakness of the Caucasian Christians was disunity IMO