If you want to develope a grip that is vice like, you have to strengthen fingers as well as wrist and forarms.
If all the individual muscles in the hand were developed to their total potential, the overall power would be literally unconprehensible.
If you don’t like flexing the fingers too many times, inorder to avoid artharitis later in life, then strengthen the fingers, by gripping a very heavy barbell in the top of the deadlift position and hold with clenched fists, until you can feel that your about to drop the weight any second. Then put the weight down and repeat another 2 times after a minute rest between each set.
If you already weight train, then do this grip work at the end of your workout no more than twice a week.
Another good exercise that focuses on the forarms, is reverse curls.
Grip a barbell as you would if you were trying to do a biscep curl. Only, instead of your palms facing up, they need to facing down.
Curl the bar up to the top position and back down, until you cannot even lift the bar. Aim to lift a weight you cannot do more than 10 reps with. Repeat for 3 sets altogether.
Bend the wrists back slightly, to put the strain on the forarms.
Now sit down with the barbell in your hands with palms facing up. Rest yor forarms along your legs with your body leaning forward, so your wrists are the only part of the arm that are not supported by the legs. Let the wrists drape down with the bar in your hands. The fingers should now be the only thing holding the weight. Bend the wrists upward, lifting the weight whilst at the same time rolling the wrists toward you. At the end of the lift, the bar will be gripped by the palms with the fingers wrapped around the top. You should be squeezing the bar as hard as possible. Now return the bar to the starting position, so the wrists are draped with only the fingers holding the weight. Repeat for 10 reps.
All last repetitions should be very hard to complete.
These exercises should never be used more than twice a week. Once should be enough to bring your grip strength storming along.
Lift explosively. Don’t waste your time with slow, smooth motion with lighter weight. That won’t give you a devastating grip. Just lift it in good form and handle as much weight as possible.
Your grip will come a long way in a very short amount of time.