Extreme lack of Hit and Pierce units? That's weird. If you'd been following the game since the beginning, you would have lots of them by now. And with more to come, there's going to be too much Hit and Pierce units.
Speaking of Slice girls, you won't be seeing a lot of them throughout all the events, because most of them already came out during the special events (Halloween's Gentian & Christmas' Holly) and also partly due to the above reason.