IN LIGHT OF MY EARLIER POST ON KNIVES, SayUncle emails that he likes this Spyderco Endura. Sure, it’s not a Claymore, but as he notes, it’s as fast-opening as a switchblade (those are legal in Tennessee) but it’s legal in more other states.
He also sends this video, which demonstrates — see at about 1:00 — that it can indeed be opened very quickly.