im not %100 sure if ths is still the case but an under 18 or possibly 21 now cant buy a knife but can go to a D.I.Y store and buy an axe, a rope and a large bucket.
as for games they need to get realistic, call of duty are war games and were suitably rated but the new one suddenly got rated an 18 which is ridiculous, however an 18 rating for grand theft auto games is definatly justifiable as in one of teh series of games one of teh missions was to get a prostitute , sleep with it then kill her and take your money back yet i bet most of teh parents demanding tehir 12 year old be sold this game were not aware of this
how do you enforce ratings on computer games when parents simply buy 18 rated games for their kids for a quiet life