Whoever shall carry a weapon or weapons concealed on or about his person, such as pistols, bowie knives, dirks, or any other dangerous weapon, shall on conviction, suffer fine or imprisonment, or both at the discretion of the court; provided that the provisions of this section shall not apply to sheriffs and their deputies, constables, policemen and town marshals, when in the actual discharge of their official duties; provided, further, that the fine under this Section shall in no case exceed five hundred dollars, and the imprisonment not more than three months.