Sec. 15-56. Sale of switchblade knives and pocket knives.
   (a)   No person shall sell, offer for sale or display any knife having the appearance of a pocket knife, the blade or blades of which can be opened by a flick of a button, pressure on the handle or other mechanical device on the handle or by other mechanical devices or gravity. Such knives are hereby declared to be dangerous or deadly weapons under this Article and shall be subject to forfeiture to the Village as provided herein.
   (b)   This Section shall not include any closed non-mechanical, non-gravity pocket knife of six (6) inches overall length or less, or any knife essential to one's trade.