The current state of "security and screening" is probably the result of high level meetings held on the subject:
So, we need to be seen to be doing something, what is really obvious every time it goes through the machine?
uuhh, little tiny scissors? yup, knives?, oh ya, nail file? yes! Guns? well on the rare occasion some idiot has one, certainly.
OK, and of those items what does almost everyone have?
well not too many people have guns and knives on a daily basis, but you know we see little tiny scissors and nail files in pretty much every bag!
Well, then we have our solution, an item we can confiscate from almost every passenger, now we look like we are REALLY achieving something!!
Right then, little tiny scissors and nail files it is!
( has anyone seen a valid survey on how many homicides are the direct result of a nail file on a yearly basis?)
Well luckily due to the extreme diligence of the current security staff this can no longer happen, but in previous ( pre 9-11) years had the purser called up to inform us that the aircraft had been comandeered by a nail file wielding gang of thugs, I would have been laughing too hard to make a valid decision!
However the solution would have been easy, as most FA's used to have as an MEL item at least one massive! nail file, said group would have been out gunned anyway.
In fact this may all have deeper conspiratorial roots, it may actually be a massive behind the scenes lobby by the press on nail people,
Take away the means to perform much needed nail maintenance, and the sales will soar!