Not true at all you can make almost any knife snap in Kydex. Ita all about the sheath. You can "curl" the sheath near the scale material near the finger choil to make almost any knife "Snap". I do it daily.What I have learned about kydex, and making it "snap": The knife itself must be designed with the use of kydex in mind. Noah nailed it.
I have had a number of folks who have asked me to build kydex sheaths for their knives....and I always have to tell them that they will have to send me the knife, and then we'd see. In reality you can make a kydex sheath for just about any knife....but unless the knife is designed with kydex in mind, it's never going to work well.
For a long time I just flat refused to work with kydex, but had so many folks requesting it for my EBKs that I finally gave in. I actually had to slightly redesign the knife pattern to make it work well with kydex, but kydex has now become the standard sheath material for my EBK line of knives. In fact since the redesign for kydex, I don't think the knives work well with leather sheaths.
This isn't Kydex.Hypothetical here but say I made a small hump on the handle or something and pressed the kydex around it. Possible? It would keep the pressure off the blade and allow for the snap no?
Also, the other thing is the way like say the Izula does it.
Seems like they compress it somewhat around the back of the blade allowing it to click in.