You can cut someone's throat with a credit card.
On other contraband, in a weekend glossy was a KEY TOOL. This cunning tool has 3 screw drivers, nail file, tweezers and a bottle opener. How do you get in on board? It fits over a standard Yale key. Would it be spotted?
Then there is a 12-section pen. It writes. It also has a hole punch, steel file, long and short cutting blades, two screwdrivers, a nail remover, tweezers, saw, steel fork and ear pick. Again, would that be picked up?
Then this nonsense about liquids? What's wrong with solids and using readily available solvent on the aircraft?
How about Maltessers or even BombBombs?