[In that moment, he realizes that he might of gone a little too far. He got the feeling that Ken had been through his own struggles, especially if he has a power like the one he saw not but a few minutes ago, but that doesn't mean Ken is from a world like his. One where monsters are just a normal part of life and warriors like him exist everywhere.

And this sort of explains the step back earlier and the mild nervousness he's sensing from Ken.]

Ah... [He pauses for a second, looking apologetic.] Careful around me, or careful of what dangers may chase us? If I frightened you, I truly didn't mean to. Where I'm from, sudden and unpredictable combat situations are more common than not, with monsters that roam the land freely attacking travelers and merchants all the same. I've been training a good part of my life to take on all challenges, and I just happen to really enjoy what I do.

[He hopes that's good enough of an explanation for Ken. Childe does feel a little bad if he had scared him, he doesn't want to make a kid afraid of him...just everyone else.]