Micro serrated scissors can NOT be resharpened. Basically all they can do is rehone the scissors edge but in doing so they will remove the micro-serration which is the very thing that makes Karen's scissors so wonderful. Additionally, if he used them to cut plastic ties on some decking material I suspect he did more than damage the scissor's micro serrated cutting edge. These scissors are manufactured to cut fabric, not plastic. I suspect he did more damage to them torquing them to cut heavy plastic ties so they are probably no longer aligned properly any more. Make the SIL buy you a new pair now.