1. You can clearly see black bandana bandat get punched, not stabbed or sliced, on chap 4, page 28, panel 1. So it's safe to assume that he either recovered because he was stronger than Ryouma thought or maybe he was someone else entirely keeping watch that came back because you can see someone(who I originally thought was Ryouma) looking through the bushes in chapter 5, page 15, panel 5. Either or it didn't "come out of nowhere".
2. Like so many people today opinion =/= fact. For me, he's surprised because he doesn't know shit about magic first of all and secondly someone he just saved turns out to be incredibly fucking strong when given the chance. In the WN he outright states as such quote;
"This girl… Did she use the same power as
that old man? That wind she created a while ago, is without a doubt similar. But
the power was different, just what’s going on??"
He wasn't surprised she used magic, he was surprised that she used it to boost his ability as well. Like I said, he's knew to magic and didn't know about physical boosting magic. Completely understandable considering the circumstance.
3. Slave magic is purposefully vague even in the novels it's not until Ryouma is gifted Wortenia and he starts an army when it's brought up again. Can't remember the exact chapters I think I wanna say somewhere between chapters 16-20 in volume 1 of the WN it's explained a little more but not by much.
You're nitpicking and using biased opinions on situations you don't like to support your claims without taking into account context, nuance or circumstances of the characters.
