If you look at the TSA list, it is not really unreasonable. You can take round nose scissors, a metal butter knife, knitting needles, nail clippers.....
The real problem with airport security is that it gives the opportunity for poorly supervised and often not terribly intelligent people, usually on pitiful salaries, the opportunity to make other peoples lives as unpleasant as theirs. When you throw in the magic word 'security' all control is lost - the lunatics are running the asylum, and any dissent by the enraged masses is immediately interpreted as a threat to civilised society.
Of topic, but can anyone confirm the anecdotal stories that UK airport police have on occasion refused to return weapons to sky marshalls when they reported for duty since they were clearly not sober?