The AW monogram is incuse on the coins and is in the field. Normally the field is the highest part of the die, but since the initials are incuse in the coin they have to be raised on the die. That makes the initials the highest feature on the dies, all out in the open. Any polishing done to the dies would tend to grind away the initials. Frankly I'm surprised missing inital WL halves are not more common than they are. I suspect they didn't do much die polishing on this series and simply replaced the dies more frequently when they clashed or sustained other damage.