Nighthawk,
Paddle angles are defined by their relation to the leading end of the boat and how they make that end of the boat change direction
Neutral angle means the blade is parallel to the keel line (imaginary keel line in most cases). The bow neither gets pushed away from the paddle or pulled toward it. “Neutral slice” is a commonly referred to part of a stroke; you simply slice the paddle from back to front or vice versa with no pressure in or out and with the paddle parallel to the midline of the boat.
Open angle means the paddle is again held with a vertical shaft but the blade is now at a slight twist with the edge of the blade toward the front a little farther out than the edge of the blade toward the rear. This open angle has the effect of pulling the bow or the whole boat toward the paddle.
Closed angle means the edge of the blade toward the front of the boat is closer to the boat then the rear edge. This has the effect of water hitting the paddle and moving the boat away from the paddle side.
In any case the boat will always move in the direction of the leading edge…whether it is twisted open, closed or neutral.
I used the term “front of the boat” but in actuality all these blade positions are relative to the end of the boat that hits a point first during travels. If you are going backwards the leading edge is the back edge.