Another problem with the death grip is that you can create some severe problems in your thumb, wrist, elbow, shoulder, neck, or back. The war-stories that you hear from the old-timers should inspire you to lighten up. My personal war-story is that I developed a tennis elbow and had to completely stop writing for several weeks and wait for it to heal. Ever since then, if I am not careful, it will flare up.
There is another thread with many tips about how to be kind to your body whilst spending hours on your penmanship.
I will add this comment to that thread - and newcomers will benefit from reading through all the tips and warnings. To those who say --- I don't care, I'm not going to follow the advice --- good luck. As a 64 year old, there are so many youthful decisions that would have been different if I could have felt what was going to happen.