there are lots of interesting ideas here by all

using the glove approach, there are some releases out there that may transfer in idea (corrosion'd always be a factor). the quick release for bowhunters, the side twist releas on pedal/shoe for bikes, a stoppered jam release (so no real jamming going out along the shaft or to the middle along the shaft.

another idea is that the person has a partial digit on the thumb and pinky, so some oppostion, some widening. what about taking the idea of a climbers jammed fist in a crack and form say reinf silicone a partial glove opened to the mid hand from the pinky and one to mid hand from the thumb then when in the 'half glove' her hand is jammed but she just twists to release. would be real quick to enter and/or release. instead of any velcro(requres the other hand) if straps around the wrist were desired, i'd play w/ some form of first just wrap under her digit so she has some control on release or some button/push that on rotation she could release also. the idea is to be able to releas w/ the disabled hand for speed, but have the 'hand fitting' to be able to start up w/ speed also.

-mick