I follow discussions on Myarmoury.com, a site that is mostly about historical weapons. I noticed a discussion of a medieval folding knife. This is most interesting, since someone had made a replica of this knife. A fine knife it is. While posting this there was no mention of the age of the original, but I am sure it will be mentioned.
http://www.myarmoury.com/talk/viewtopic.php?t=27726
http://www.myarmoury.com/talk/viewtopic.php?t=27726