I do remember being quite frustrated the first time playing and repeating that battle 4 or 5 times before squeaking out a win. Bejeweled is a cruel mistress it's one gem cascade away from you losing 1/2 of your health in that battle. If you want to make it easier maybe swap overhand blow 2 with something less potent?
You are right though the more you play it the easier winning becomes I'm 5/5 with it now. Winning strat seems to be eliminate all the red gems as possible, take every 4x/5x moves and only go for the gems you need when there's nothing else.