A prisoner/geek in Wales had his secret stash of matchstick weapons, including the Buster Sword and Squall's Gunblade from the Final Fantasy video game series, confiscated because:
"...the realism of the swords presented a threat to staff safety, not because they could be used to send the staff back to the Lifestream, but because they look real from afar and could be used to threaten people."
This guy will have a sweet job waiting for him when he gets out-making replica weapons out of balsa wood.
Link
I guess you don't really understand that in a prison environment, there are many dangerous individuals. If you seriously cannot see why having fake, vaguely realistic-looking swords in a prison environment could be dangerous, you should be locked up for your own good.