I'm a librarian who loves anime, manga, and reading a wide variety of genres.
Nazleen's wondering why her brother seems to be fine with hanging out with Zaktar, considering Zaktar and his people killed her brother's friends and comrades and almost killed him.
"That was war, Nazzie. It wasn't murder."
The fighting wasn't that long ago. Also, it's been indicated several times that Zaktar, at least, is skilled enough to know how to hold back and simply disable his opponents, rather than kill them. There's at least one character that would still be alive if Zaktar hadn't deliberately opted to kill him. We're just going to brush that off as no big deal?