Hey what should I use to shorten the blade from the tang side? There is an uneven hone on the edge, about 2 inches are level and 0.5 inches is about 2-3 mm shorter.

Should I flat file, round file, or how to shorten blade?

Thanks, was hunting around and didn't see what I should do. Here is a pic of it from another post.

Ern 1720 antique store find, first hand sand.