Blacksmith: "You saved my son's life. Please take a weapon from the store for free!"
MC: "No, I couldn't do that!"
Blacksmith: "You say my son's life is worth less than a spear?"
MC: "That's exactly what I'm saying!"
That kind of knife is no good for fighting. It might be good for cutting food and such as it would still cut even when duller due to the saw edge. However, in a fight it would unnecessarily get stuck in the opponent's gear, tendons, and bones.