The saw blade has a specific thickness different from the classic blade. Only 18 cm Opinel saw blades are sold as spare parts. I didn't do this but I saw some #12 mods with saw and blade.
Welcome to your English reads fine to me We have a few members from Belgium Don't know much about Opinels other than the 3 that I have so I can't help, sorry Hope that Michel's answer helped though
It´s a bit of work but it can be done