Hi Peter, the Spyderco Jester is a nice little keychain knife. That it has FRN (Fiberglass Reinforced Nylon) handles and no metal bolsters is good if it is going to be carried attached to the Arc AAA, so that it won't beat up the aluminum.
I don't carry my Arc AAA on my keyring, I carry it attached to a Victorinox SAK Classic. You can see it does a number on the plastic scales.
But my 2 year old Arc AAA is still in very good condition. This is the 2nd Vic Classic I've had attached to it.
I noticed at the Spyderco website that they are now offering a Jester along with a Photon II LED light with the Spyderco Spyder on it.
Spyderco Jester FRN and Photon light
The Spyderco Dragonfly FRN is, in my opinion, a better knife than the Jester, but it is atleast twice as much at retail pricing.
Spyderco Dragonfly FRN
The Dragonfly uses the better AUS-8 stainless steel, the Jester AUS-6, which is very common and does fine, but the AUS-8 is better.
Importantly, the Dragonfly's blade length is well under 3 inches at 2 5/16", though the Jester's is 1/16 inch under 2 inches at 1 15/16". Many states or principalities have a blade length limit on pocket knives, generally most that do require them to be under 3 inches. But a few require them to be no longer than 2 inches. Just another consideration.
The Dragonfly feels better in my hands than the Jester. The choil (finger cutout) at the joint gives me a good, safe place to put my forefinger and the thumb rest above the opening hole on the blade gives good control. The little bit of extra length in the handle over the Jester will make people with larger than average hands happy and will make it that much better for those with average or smaller hands. The difference in closed length is around 1/4".
The only reason I bring up the Dragonfly FRN is in case you don't want to follow Spyderco's Jester with a Photon light pairing. The higher cost of the Dragonfly may exclude it from many's consideration, although I'd buy one with Arc Flashlight on it.
Britt