Good point on the strong grip part Rob. I totally agree.
This is why any "stripping" is done after the attacker is pinned and secured on the ground and unable to go anywhere. Then one can utilise a few things like locks that isolate and weaken the muscles of the hand forcing the grip to loosen like Nikkyo (Kote Mawashi), Sankyo (Tenkai Kotehineri) or Kotegaeshi or something we do where the meaty part at the base of the thumb is placed on the inside of the attacker's four fingers and a pressing/rolling action is used to roll the knife out of the attacker's hand - sort of like rolling his fingers like dough, ending up with the knife in your hands instead - kinda hard to explain. This also serves to isolate the fingers and get the knife out.
Good question and comments btw.