If you want nothing sharp you would have to ban duty-free bottles. That isn't going to happen.
Not necessary - many DF shops (and Spanish supermarkets in tourist areas) sell spirits in plastic bottles, presumably because of the weight, but you couldn't smash these for the glass and they would be much less effective as a cosh.
Pens, however, are a different story - I wouldn't want my slim steel pen held to my throat, but no notice is taken of these.