this may be late however....enjoy....
In PA Title 18 "Crimes & Offenses" appears to be the relevant statute. In
section 907 it talks about "Possessing instruments of crime" and states:
"A person commits a misdemeanor of the first degree if he possesses a
firearm or other weapon concealed upon his person with intent to employ it
criminally." Where a weapon is "Anything readily capable of lethal use and
possessed under circumstances not manifestly appropriate for lawful uses
which it may have."
Section 908 covers "Prohibited offensive weapons" and states:
"A person commits a misdemeanor of the first degree if, except as authorized
by law, he makes repairs, sells, or otherwise deals in, uses, or possesses
any offensive weapon." But with the exception "It is a defense under this
section for the defendant to prove by a preponderance of evidence that he
possessed or dealt with the weapon solely as a curio..." or possessed it
"under circumstances similarly negativing any intent or likelihood that the
weapon would be used unlawfully." An offensive weapon is defined as "any
bomb, grenade, machine gun, sawed-off shotgun, firearm specially made or
specially adapted for concealment or silent discharge, any blackjack,
sandbag, metal knuckles, 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."
[the above is taken from: http://www.moonface.com/title18/title18.htm]