I regularly (twice a month) go airside LHR Terminal 1 to service some of the stands there.
I carry a variety of knives including scalpels, stanley knives, lock knives even a 10" serrated bread knife (it comes in useful sometimes) in my toolbox, also have a wide selection of razor sharp chisels and any number of other tools that could easily become offensive weapons.
None of this is questioned as I need this stuff to be able to do my job (I'm a carpenter)
I do not get checked on my way out.
Therefore I sometimes wonder about all the other staff I see there and how easy it would be for one of us to conceal a weapon airside for someone else to pick up at a later time.
It makes the hunt for nail scissors seem farcical.