So, yeah. The MC had no reason to sound suspicious for knowing how to use these gas canisters.
"How did you know these canisters will explode!?"
"When I was attacked by the imps, I just threw w/e I had near me in a panic, and it blew up after interacting with that fire-horse-thing's firey mane."
"Oh okay."
... o_o
It's funny to see how the author can do nice fluff, but be shit when it comes to other things. It's weird to begin with that these canisters were at the castle.