It states 1 damage per Blight. Since there can never be more than 1 blight on a space, does this signify it does 1 damage per blight token that is on the board? There can be more than 1 Blight per space. If you want to add Blight to a space that already has Blight, you do add it to that space, and then it cascades and also add one Blight to a neighboring space. (See the rules on p. 9 and p. 15).
Did I correctly get at your confusion?