handgunlaw.us is such a nice resource. Under Misc. Information for PA:
Does Your Permit Cover Other Weapons Besides Firearms? NO § 6109.
BUT, you have to look at the definitions involved.
"Offensive weapons." dagger, knife, razor or cutting instrument, the blade of which is exposed in an automatic way by switch, push-button, spring mechanism, or otherwise, or other implement for the infliction of serious bodily injury which serves no common lawful purpose. No Blade Length in PA Laws.
With Philly having an extra restriction:
Any knife or other cutting instrument which can be used as a weapon
That should give you a good start. There could be other city ordinances, handgunlaws.us just lists the large ones.