Let's say you decide to carry a knife. Maybe you're going fishing. Maybe -- since you're not carrying a fishing pole, and since this is what you'll eventually tell the officer -- you're carrying it for self-defense. It doesn't matter.
First point: Don't conceal it. That's a crime. It can get you five years in prison.
Second point: If you ignore the first point, when you get on the trolley, buy a ticket. Otherwise you might well get stopped for not having a ticket, they'll spot the concealed knife, and prison will be your destination. Your effort to cloak yourself in the Second Amendment to avoid this fate will completely fail.
Two dollars to save five years. Best investment you'll ever make.