The blade should be extremely flexible if you are going to make full use out of the finger hold on the handle. The fingers and blade are intimately connected. It only requires a very light touch of the fingers to manipulate the blade.
With the old wood blades you could feel the blade move from the oversquared position to the squared position in the water. It quickly becomes an unconscious movement. The blade just sinks into blade depth at the entry and the feel is partly in the blade and partly in the shoulder girdle.
At the other end of the slide the important movement is the blade coming a quarter out of the water and then this is where the feather begins. This requires a slight subtle downward movement of the hands, ever so slight.
There is a slight pressure on the handles as the blades are carried from the release to 3/4 slide and from 3/4 to full the weight shifts from the handle to the weighted blade. This allows the blade to drop in unceremoniously at full reach. It is an unconscious movement.