"Offensive weapon"?

So the naked guy on the equestrian statue in London's business district had his day in court. (NSFW images at HuffPo, if you'd like to see them.) I kind of enjoyed the spectacle he provided. Even in still photos, it's evident that this was performance art. And I find it funny that one person without clothes can result in such a ruckus. The story about the court scene revealed an odd fact.

"Motrescu, a Ukrainian citizen of no fixed address, was convicted Tuesday of possession of an offensive weapon, criminal damage and a public order offense. A magistrate at Westminster Magistrates' Court sentenced him to 12 weeks in jail."

One wonders what "offensive weapon" a naked man can wield. I'm hoping they found a pen-knife in his travel bag, or something. Otherwise, this is an exceedingly strange charge. Perhaps they're just overreaching; he's said to have pulled a piece of a sword off a statue and then bit it. (I can't imagine what that means.) Is that the "offensive weapon"? Weird.