We had document boxes at Waddo. They looked like ammunition boxes and had watertight seals etc.
The boxes were taken to the Foreign Office where diplomatic seals were added and then brought back to Waddo to be filled. That way it avoided couriering material unnecessarily around the country.
The seals were attached in such a way that they only 'appeared' to secure the boxes.
Once, on returning from overseas, an eagle-eyed customs official insisted on looking in one of the boxes. No dice. Impass.
The solution was for box and courier to be locked in the secure cage until a senior, and appropriately cleared, customs officer could be brought. A couple of hours later he came, words were said, and box and courier were released. The box was never opened.
Rather than trying to bring the weapons into Qatar, had they stayed in the aircraft, airside, with a crew member/RAFP, is it possible they would have been OK?