What makes a weapon a terrorist weapon is the way it is employed, not the weapon itself.
If someone used that bow and arrow from the upper deck and fired into a crowd at a packed stadium...you have a terrorist weapon. The idea of a terrorist weapon is to induce terror.
If effective, the crowd can kill more of its own in panic, trying to get out of the way than the killer gets with the weapon, but the real measure of effectiveness is what changes are made to a society as a result.
Here, the terrorists won. We have given up our right to be free from unreasonable search and seizure, have created whole agencies to spy on our own people, and tossed our Rights away wholesale while the most likely perpetrators of terrorist acts go through unscreened so we don't appear to be profiling. Not only ineffective, but incredibly expensive theater to try to convince the masses they are 'safe'.
...And we have yet to secure our borders.
Precisely!
That they DID get THIS kind of punishment for this kind of WEAPON is unconscionable. And I'd be saying the same thing if their names had been Achmed, Mohammed, and Abdulla.