I would not say the knife is ruined if you plan on using it and can get it cheap. The knifes performance would not be hurt by the thong hole being enlarged. If a knife needs to be modified to fit your purpose, I see nothing wrong with it. Although once it has been modified I would not to try and sell it for something its not.
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Jimmy Bedgood RKCC# CM-050 RKS#5929 HOG Member www.bedgoodknives.com