If I may... Navaja is straight translation to spanish for folding knife. And the kind of knife called "navaja" abroad is a traditional type from Albacete. Law in Spain goes more or less: if it's under 11 cm, single edge and not auto-opener it's legal. No double edge for fixed blades. There's an amendment to the law that forbids weapons at public places and leaves it to the LEO's judgement whether to confiscate and fine you. IIRC law in Portugal is pretty similar...
Indeed. Navaja is the spanish translation for folding knife. In portuguese we have two words: navalha and canivete. If you are talking about a shaving razor, you say "navalha", if you are talking about a multi-tool pocket knife (like a SAK) you say "canivete", for everything in between you can say both navalha and canivete. Law in Portugal is similar to the spanish one. If the blade is under 10 cm long, it's legal. Balisongs, auto-openers and throwing knives are considered illegal and you can't have them at all, not even for collection. Nowadays in Portugal we are loosing the pocket-knife tradition. This means that in urban areas people don't have a blade in their pockets anymore. But in rural areas it is very common. The most popular model is the "straight" pocket knife. In portuguese it is called "navalha direita". Here's a few pictures I took today. This was my first pocket knife with a horn handle. If you ever see a pocket knife in Portugal, chances are that it is either a SAK or one of these. Usually they are made with plastic handles, but the traditional material is actually cow horn. This one is not with me all the time, but I have it in my car, and I use it mainly for food (fruits, etc.). These pocket-knives have different sizes, always measured in centimeters. This one is a 15 model (15 cm length while open), which is the most popular. However, you can find sizes ranging from 13 to 23 or even higher. Here's a younger sister, also a 15, with a slightly different look: Steel is 420 because it's not expensive and it has a good edge, if produced with a good thermal treatment. It has good resistance against oxide, which is mandatory since many people use these knives for fishing or agriculture. Usually these knives are sold with a colorful plastic handle (red, yellow, blue, green, white or black) and will cost around 5€. However, something like the one above will cost around 20 to 25€. Don't expect the manufacturing process to be something like Victorinox. These are made with the help of machines, but in the end there's a man (or woman) putting the pieces together, sharpening the blade, polishing, riveting and making everything look as you see in the pictures. I think I have some pictures of the factory somewhere, I will try to find them and will publish them later. Hope you like the "direita" pocket-knife, I will post a new model in a few days. If you wish to know any more details, or maybe see a photo of a detail or from a different angle, just ask! Cheers.