Not sure, as they long preceded my tenure and I've not worked on Armenia (ie, I'm not really the guy to answer this), but I've the impression they're meant to form a sort of parallel to Roman legionaries, showing a type of unit with simple shortswords derived from Hellenic and Persian equipment and combat traditions. I know you've done work in this area MP, so you may well know the frequency of sword finds in the Caucasus.
An additional note:
There will very likely be an additional and exciting thureos-equipped unit for late-game Hayasdan. MP, you can probably guess it, but I'd rather you didn't spoil the surprise.
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