Following today's events in Egypt, where your Secretary of State and his people were put through a metal detector before being allowed to visit the Egyptian President, you should issue uniform swords to all ranking diplomatic personnel. You have diplomatic immunity, after all; and the sword remains a powerful symbol where you are going.
Not ceremonial swords, either. Real swords. Albion makes some good ones. Make it clear that you are carrying a weapon, and defy them to stop you.
If you need any assistance in effecting this policy, don't hesistate to write. Actually, you probably should anyway.