That "and just hit as hard and often as I can!" thing...ye gods. That seems to miss the point of why people have techniques and fighting styles.
Also, just because you're not using a technique doesn't mean A) that you have no body language, B)that you've just had the tar beaten out of you, C) that Cass isn't ridiculously strong and tough and fast for a normal human (didn't she once outrun her own batarang somehow?), D) shut up, "good ol' fisticuffs".
Anyway, while the fight between Cass and Supergirl is awesome (until the ending), I'm not sure how she didn't get impaled after Kara kicked her into those spikes.