the new battle system doesnt have anything to do with this, because Block system above is a separate system it wont interfere with combat system else I I wont post it here now but wait until 1.21
Have you played with the new battle system to know if it will interfere or not? Do you know how busy will you be handling combos and enmity generating skills to know you will have the time to put up or down your shield arm? Are you able to do other skills with the system you are suggesting should be implemented?