Jorvik, am I correct in my belief that locking folders are illegal in the UK? (Ain't government in loco parentis for grown adults wonderful?) If so, I guess that those non-ratcheting navajas are for you all. But that more or less destroys the historical nature of the beast, if you follow me. Part of the character of the navaja is the ratcheting sound as you open it. I have read that the sentries in Napoleon's army in Spain back about 200 years ago were terrified by that sound as it meant that they were about to get their throats cut by the original guerillas. It is that sound that gave the navaja its nickname, El Carracca".
In any case, you may want to look at this website. I have often drooled over their navajas and their French Laguiole-style knives which seem to be a related design. What is a little known fact is that Spyderco once made a Laguiole style knife. I would really love to have one, but they are all collectors' pieces and priced accordingly.
BTW, you mentioned the stiletto knife. Those were the standard switchblade in the teen exploitation films of the 1950s, the original being "Blackboard Jungle". Those flicks eventually got switchblades banned federally as the weapon that was going to end civilization as we knew it.
They were notoriously weak at the pivot between the hilt and the blade. There is a scene in the above flick where the teacher, played by Glenn Ford, takes one away from the lead punk, played by a very young Vic Morrow, stabs it into a desktop and backhands it, breaking it off at the pivot. They were junk and I sincerely doubt that the manual versions are any better. But the above store has one listed under "Italian Knives."