I'm not a legal expert but I can give you the criteria i use to myself based in my incomplete knowledge of the portuguese weapons law
1- Any knife with a blade length of 10cm (~4in) or less are free to use.
2 - There's no restriction in what concern on the locking mechanism. In this point is different of other european legislations.
3-There also no restriction in the opening mechanism unless is an automatic. So are only allowed knifes with manual opening or unassisted opening.
4-Automatic knives, karambits, OTF, Balisong are clearly forbidden in the law and in any case. The forbidden of automatic and the others has to do with the fact that kind of knives are made with the sole purpose to use as a weapon. That is one the basic principle of the law. Anything manufactured or use as a weapon is forbidden or requires special licenses or authorization.
5 - The knives with blades over 10 cm can be used but they can only be used in the context they where intended to, so a kitchen knife is allowed but in context of food prep. The Bushcraft Knives or "facas de mato" the term used in here if used in this context are allowed or the machetes that i use in professional context. In these cases what i do is to transport them in way that cannot be considered a threat. In it's sheath, in the car trunk.
Finally let tell me one peculiarity of portuguese law. Any blade with disregard of his lenght or construction, are legally considered as a weapon if used as such to threaten or do harm and judge as that.
In relation to your question i think it has to do with Cold Steel server not allowing request from Portugal. In fact this issue, i think, is related with the EU privacy rules. i had some similar messages from other US based sites. But you can access de site trough amazon.com
