As stated earlier, it is essential to keep the bow hand as relaxed as possible during and after the shot. Every movement while the arrow is still on the bow will result in a large deviation on the target, especially on longer distances.
A bow hand that grips the bow firmly will tend to move more during the shot than a relaxed hand because of the required extra muscle control. On the other hand, if you force your hand to be open by stretching fingers, this also will mean that more muscle control is necessary. Both styles are impossible to maintain over longer periods of shooting because it is impossible to use the same muscles in exactly the same way every time.
We can see that it is very important to maintain a relaxed bow hand throughout the execution of the shot.
When relaxing a hand, the fingers should be curved, not straight. Just try laying the back of your hand on the table and relaxing it. You will see it right away. It is normal that fingers are curved while holding the bow. This does not necessarily mean that they grasp the bow. When your hand positioning is correct, one or two fingers will not touch the bow. You can probably bend your little finger and ring finger without touching the bow. See also figures 2 and 3.
Holding the bow is here not really the right word. The bow should more or less 'rest against' the hand, without gripping the bow.