In late antiquity many IE groups (India, Iran, Armenia, Germania, Rome to degree) converged to a triad (trimUrti) of “primary” deities. The Armenian one is given as Aramazd, Anahit, and Vahagn. It is not identical to the Iranic one despite the Iranic origin of the names. It seems the Iranic names were superimposed onto the original Armenian ones. Thus, it may indeed be correct to assume that behind vahagn was the original Armenia indra-class deity.
It also seems Armenians had a more typical, veda-like aindra religion distinct in its configuration from the religion of core Zoroastrian one. This might have favored the easy establishment of the Indian dynasty in Armenia for a while (followed by Gregory’s classically Abrahamistic crusade on H shrines in the region).+++(5)+++ However, on the other hand it might also suggest that in the more western reaches of the Iranosphere, like where the Commageneian dynasty arose, there was a remnant Iranic version of the old religion that made a backdoor entry following the Zoroastrian counter-religious coup.
The aindra nature of the Armenian religion is also indicated by lucky fossil preserved in the form of Tiridates words in their tradition, transliterated as:
k‘aĵu‘tiwn hasc‘ē jez i k‘aĵēn Vahagnē
“may valor come to you from valiant Vahagn”.
The primacy of vahagn in that tradition is quite distinct from the Zoroastrian one, where he is not part of the post-counterreligion triad. Interestingly, there was a major Armenian temple of vahagn at a place called Tarawn which itself might have acquired its name from the Anatolian equivalent of the indra-class deity.
Interestingly, Armenians equated the Iranic rudra-class deity with a deity of their own (name lost) & homologized him with Greek Apollo. Armenians had a major temple of his at Artashat associated with dream-augury & scribes – note parallels to Apollonian oracles of the former.