I'm sorry, but I think it is more unfair that he should have to spend more of his money to return and correct what he should have got in the first place. You want him to spend even more money to buy a sharpener to correct a problem that shouldn't be there at all.
If you purchased a new car that needed a fender re-painted, would you purchase the tools that are needed to repair it yourself, and go on to correct it yourself, or would you bring it back? The value of ones purchase should have no bearing on whether it is okay to accept it or not if the product is defective.