Easy way to dull dull knife for prop
Dulling a real knife? Do you have photos of the one you are planning on using?
This is the knife I have
Striking the edge across a very rough surface such as brick/cinderblock continuously not to extreme or hard though or you will chip the blade up, then using a high grit sand paper to also buff and rub the edge off. A power sander would ultimately work best but if you don’t have one laying around those methods will work it just might take some time.
You can firmly run the edge across a sidewalk or curb until you get the results you want. Will work quickly!
Advice given by Kurse and TQuin is on point. Just make sure it is completely dulled out if you plan on bringing it out on Halloween! Not sure how they are in your state but in NY they really take weaponry seriously and even certain props will get the cops called lol