As promised on a previous thread, I have spoken to my policeman student about the carrying of kubatons.
It turns out that Khayman and I were both misinformed. They are neither legal even if on a key ring nor is this a "grey area".
Apparently, the law is very specific on this and kubaton are in the same category as nunchukkas; fine if being carried to and from the dojo for training purposes but an offence if carried at any other time.
Just thought I would pass it on.