When last I flew out of Santiago, I completely forgot to pack my Swiss army knife in my hold luggage. While going through the security check the knife was spotted as my carry-on bag went through x-ray. The security guard removed it from my bag, opened the blade and measured it against a ruler set into his desk that was just about the exact length of the blade. With that done, he closed the blade and handed it back to me.
Santiago airport clearly has a policy relating to size and type of knife that can be carried onboard, I can only assume the policy is similar to law we have in the UK for everyday carrying of a knife in public. I can’t recall the exact length (have 6cm in mind but could be wrong) but it matches that of a standard swiss army knife, the knife must be also be of a folding type with a non lockable blade. In the UK one has to demonstrate good reason to be carry any blade that falls outside those regulations.
No idea if it’s a general regulation at all airports or if each airport sets it’s own limits. Whatever the case, I was delighted about Santiago’s policy because, having carried on many travels, I’m rather fond of the little knife and would have been very sad to lose it.
As for taking a Swiss Army knife on your Camino, I find them jolly useful and wouldn’t be without one.