SEC. 6. If any person shall carry concealed upon or about his person any pistol, revolver, dirk, dagger, slungshot, knuckles of metal, or other deadly or dangerous weapon, within said city, or shall, in the presence of any one, exhibit such weapon in a rude, angry or threatening manner, or shall have or carry any such weapon upon or about his person while intoxicated, he shall upon conviction thereof be fined not less than five nor more than ninety dollars: Provided, That nothing herein contained shall prevent any police officer, or any officer or person whose duty it is to execute process or warrants, or to suppress breaches of the peace or make arrests, from carrying such weapons in the necessary discharge of his duty.