Got full body searched because I putted my hand in my pockets during an altercation... It was minus 20 out there my hands were freezing that's all, and they took away my beloved cadeteven if they could not press any charges. That was in the 90`s in Montreal. So I`m pretty sure today I could have trouble with a butter knife.
You probably would, if you went for your pockets while being approached by the police.
Where I come from, that can get you shot, even if you have nothing in your pockets, so I'm not sure how it is "knife rights" related.