Found this warning on a U.S. Consulate site

"If you carry a knife on your person in Mexico, even a pocketknife . . .
  • You may be arrested and charged with possession of a deadly weapon;
  • You may spend weeks in jail waiting for trial, and tens of thousands of dollars in attorney’s fees, court costs, and fines;
  • If convicted, you may be sentenced to up to five years in a Mexican prison.
Claiming not to know about the law will not get you leniency from a police officer or the judicial system. Leave your firearms, ammunition, and knives at home. Don’t bring them into Mexico"

That's enough even to scare me off from a "sgian don't."

Probably gonna be too hot for kilt hose anyhow....but never dreamed the Mexican laws were so strict.