Generally speaking the only thing that will give a bow, by itself, excessive hand shock is too much outer limb mass. The worse offender is having the inner limbs doing all the work and the outer limbs stiff and unbending. When the string slams back home any energy that remains in the bow will travel down the limbs making them bow outwards. If most of the limb is working then this remaining energy will be distributed throughout the limb with very little handle movement. If the only part of the limbs that are actually working is near the handle then this will concentrate the remaining energy in that area and tend to make the handle bounce back and forth in your hand.
Limb timing has been talked about before but this is very ambiguous. Unless your bow making skills are very pour you should be able to easily tell whether one outer limb has more mass than the other and that is one of the very few things, if not the only thing, that can actually affect limb timing. The other thing that may affect limb timing is having one limb much stronger than the other and this is also something that is very noticeable, this one is very iffy though as a stronger limb would have more mass which would tend to slow down it's return making it pretty well the same as the weaker limb.
