I agree with an earlier poster who said that a bottle of alcohol bought on board would make a fine weapon. Also, a full sized laptop can weigh up to 2Kg. I have not tried it but I reckon that hitting someone on the head with the flat side - or using the thin edge swung with force into their neck would give the receiver pause for thought.
I have had an item with a very small dimension removed because, I think, they were too busy to inspect in detail and just binned it. As well as allowing through something that could certainly puncture a jugular vein. I also had a time to return to the main terminal. Many moons ago at LTN, the X-ray of my shoulder bag turned up a pair of small wire cutters that had got lost inside a padded liner and could not be felt. The actual blades were less than 2cm but the item was decreed unacceptable. I went back downstairs and bought a padded envelope and stamps, and posted it to myself as it was very good pair!
The staff did not appreciate my thanking them for finding them for me.