No to grabbing
you're likely to get cut, so make sure it's on the backs of your hands and forearms and not the palms/insides, outer leg rather than inner leg and so on. And finish up quickly before you go into shock :)

I met one guy who took an attacker's knife out of the equation by jamming it into his thigh and holding it there while he punched the crap out of him. He's a very scary guy.

Yup, 10" or so is the cut-off between small and large knives - whether you have a realistic prospect of getting past the blade with your bare hands. Most etymologies of fencing indicate the sword is your protection, rather than your weapon - you keep it between you and your attacker.
( Flapjack I spay a little mare for you, Fri 19 Jun 2009, 11:18, archived)