Minors can't carry any weapon legally in Baltimore one hour after dark to one hour before dark-and seems concealed carry of knives is illegal.
c) Prohibited.-
(1) A person may not wear or carry a dangerous weapon of any kind concealed on or about the person.
(2) A person may not wear or carry a dangerous weapon, chemical mace, pepper mace, or a tear gas device openly with the intent or purpose of injuring an individual in an unlawful manner.
(3) (i) This paragraph applies in Anne Arundel County, Baltimore County, Caroline County, Cecil County, Harford County, Kent County, Montgomery County, Prince George's County, St. Mary's County, Talbot County, Washington County, and Worcester County.
(ii) A minor may not carry a dangerous weapon between 1 hour after sunset and 1 hour before sunrise, whether concealed or not, except while:
1. on a bona fide hunting trip; or
2. engaged in or on the way to or returning from a bona fide trap shoot, sport shooting event, or any organized civic or military activity.
http://opencarry.mywowbb.com/forum28/2526.html