So I spent about an hour trying to defeat this guy. I know that he's way too powerful for me for a head on fight, but I found that he was able to be cheesed a bit by hiding behind a post and just kinda peeking out, baiting shots. Got him down to 20% once that way, in fact. Then, on a whim, I decided to try to do a steathy takedown, see what would happen. Wasn't expecting a prompt at all, turns out there was... And it was kind of a powerful option.
https://store.playstation.com/#!/tid=...