Well, we've seen Barry phase through Kara in last year's crossover so that's definitely possible. As for the hand shank, I don't see why it wouldn't work. Of course Kara and Clark are far more denser than the average human but we saw Thawne leave a visible dent through Ray Palmer's ATOM suit using the vibrating hand. The ATOM suit was stated to be pretty durable so that's quite an achievement, if it can rip through that suit with ease then that should also be an indicator that it's possible with a kryptonian too. As someone said, it also might be a matter of vibrating the hand at the right frequency but yeah I don't see why it wouldn't be possible.