Weeds in a lawn are easy to kill using granules but you do need a proper applicator, I do like the screwdriver and Jeysfluid idea - a proper applicator.
Coarse grass is different, if frequent mowing does not produce the result you want, rotavate and returf is the best answer but it is expensive. Even then it needs to be maintained because weeds will invade over the years.
From sinner to saint, quits a transformation.
