The ancient armors are some crazy pieces of magitech.
Pendrag's armor was specialized in attack, not just close-range combat, but mid-range, mobility, both on solid ground and aerial.
Kynvelin's, on the other hand, may seem like just a defensive armor... but it has area control abilities and bombardment... that is an armor made for war.
Whoever forged them was a freaking genius, maybe it was more than one person... that would be a refreshing take on the "talented smithy" troupe, that instead of one person, it was a group of talented people... I would like that.
Considering the armor communicated with Aquill here... maybe it has the ability to choose its wearer... but what are the qualities it wants is another story... Doc wasn't the best example of virtues when he activated his XD.