In this manga slaves make some sense because MC tactic rely on manpower, and slaves are basically just cheap manpower.
In some other manga, especially the ones that have romance, slaves are just lazy writing. Female slave is an established motif so it's easier to write story about.
MC had passed out several times up until this point, and each of those time someone have to take care of her, including changing her clothes. It would be weird if they still don't know her gender after all that.
Monster =/= wildlife. There isn't any depiction of what kind of monster there are yet, but if there're goblin, orc or kobold then it make sense that people would fight them with swords. Not to mention, there's magic in the setting of this manga.
"Do you know what the different between a sword...
There're monsters in the setting of this manga and so it could be that he only make and repair weapon for the purpose of fighting monsters. This is a fictional story after all so the author probably wouldn't add a cognitive dissonance character for no reason.
My guess is that this chapter was probably translated from the spanish translation instead of directly from the raw. I saw a MTL subtitle of an anime episode once and it's also full of upside down question mark like this.