The swing itself is to create the correct impact in as simple a way as possible. The goal is to get the club, body and arms at impact as it they were at address.
Keeping in mind that since the upper body winds against the lower, the lower will unwind. Therefore the
hips may be slightly open at impact but certainly not the shoulders. However this is a result.
Posture angles should maintain thru the swing to give the best chance at a repetitive impact.
Concerning the hands and arms: keeping the angle formed between the lead arm and shaft thru the
swing keeps the club face square to the arms. That also means that the club face will then be square to
whatever path you swing the club on.
As far as the overall motion, there has to be a combination of horizontal and vertical movement due to
the position of the ball at address (ball is to the side and on the ground). The hands moving up and down
create vertical movement, shoulders create horizontal. It is in the combination of these and keeping the
shaft parallel to the original address angle where consistent repeated impacts lie. Forearm rotation
becomes the key to swinging the club parallel to the original shaft angle from address.
This will create a shallower angle of attack allowing the shaft of the club to flex properly thru impact
creating more distance.