I'm in no way an expert in indo-iranian languages, but -bara should mean troop/group of soldiers, with the previous compound word denoting the type. Therefore Hadabara could very well mean cataphract (like Grivpanvar means neck-guard wearers).
Seeing how Ysaninu Aysna is the name for the early unit, it could be the names were misplaced, but I really don't know...