If a hand was suddenly chopped off while holding something, would the severed hand still hold a grip?
(Disclaimer: I have no personal or medical experience of cutting off hands, or any other body parts, so this is purely theoretical.)

It seems unlikely, since most of the muscles that provide the gripping force are in the forearm and are transmitted via tendons in the wrists. Try gripping something forcefully* and notice which muscles tense up, and how the tendons on the inside of the wrist transmit the force.  Cutting the tendons would eliminate the force.

Of course anyone who's done much fencing knows that you don't grip with too much force, because that interferes with the fine control provided by the fingers.