Barlow knife quote meaning in Mark Twain's Adventures of Tom Sawyer?

Question

> True, the knife would not cut > anything, but it was a "sure-enough" Barlow, and there was > inconceivable grandeur in that - though where the Western boys ever > got the idea that such a weapon could possibly be counterfeited to its > injury, is an imposing mystery and will always remain so, perhaps. Doesn't seem to be your normal construct in regards to **"...such a weapon could possibly be counterfeited to its injury..."** What does "**to its injury**" mean here?

Answer 1

A Barlow knife, the knife given to Tom, is a cheap pocketknife of poor quality. It's lousy, it won't cut anything. "such a weapon could possibly be counterfeited to its injury" is referring to the fact that because the knife is so lousy, making a copy of it would make it worse.