Wake up, Kylar!

See, this separate Kylar basically assaulting Kylar has me thinking that there's something else going on here. It's not just Kylar recounting his memories and feeling bad: something is manipulating him. Now, it could be an overactive imagination based on... is he knocked out somewhere? Like, I'm absolutely certain there are sins weighing heavily on Kylar's back, because he is a knight in service of an expansionist, war-mongering king. You're gonna do bad stuff if that guy's your sovereign. But... there's already magic going on, and seeing as Kylar is an agent that is probably nominally opposed to the people who are (probably justifiably) opposed to the king, who's to say they wouldn't inflict a little additional psychological trauma on someone hiding secrets this big?

It is a possibility but it could be simply his guilty conscience that catching up with him.

True, but I wonder why now

In story reason : He's been feeling it for awhile and being confronted face to face with an active rebellion against the crown/failing mission weighs heavy on his subconcious, causing a nightmare fueled by guilt,shame and past experiences.

Real Life meta reason: Because showing this now will help juaxposition the arc he is about to go through as we introduce this new faction delving deeper int the geopolitical and historical aspects of the story - Kylar is a complex character that didn't get the context needed in prior pages to fully explain his motives and we've smoothed over the narrative direction behind the scenes.

the guilt makes sense because he's been through a lot!