If you payed attention to their behavior they're pretty intelligent in terms of combat.
Now based on gameplay you vs promy knight their ability to dodge, shoot + dodge, evade (phase retreat), aggro (blade melee + jump or phase charge). The only thing that really separates them between other AI like Elites and Brutes in H3 is their inability to interact with objects to use like turrets and vehicles. Now when you compare the Elites and Brutes using Jetpack for ex. they take time for planning in attacking and retreating moving from point A low ground to point B high ground to get a better position to either heal or regroup OR go for the offensive. This also can be said for how Brutes defy gravity to get a hit on you when berserk with aim assist. Promy knights have to target you, get into berserk mode, and position themselves to get a clear straight shot. They don't phase charge you and insta-kill with aim bot. It's either a swing + hit or swing and a miss. There's also a big lack in using plasma pistols to better handle them quicker. That was purposely designed for you to use their own class of weaponry. Not really fun.
The promy knight with the incinerate cannon is lame though. And knights don't visually and vocally give you an advantage to predict behavior in your favor either.