Grip strength is a huge part of Judo. Whether you are trying to pass someone’s guard, obtain back control, or keep them from doing so to you, a deciding factor could very well be your ability to hold onto
Good advice, but there is one more. Hit that bastard hard the first time, and before he can shake it off hit him again and again. Knock him flat and kick his face in. It's not cheating or being a dirty fighter, it's called winning. Unless he's out cold never underestimate the guy. Back away after the fight is over and watch for anybody that may want to step up to the plate.