If you're looking for something similar to the Pin Slasher within the Columbia line, you probably can't go wrong with the Cool Noize. It'll be a little weaker overall, but has a medium strength core, with a decently strong cover. It is a solid so will still be nice and smoooth.
If she likes the Ebonite line, and wants something to compliment the Pin Slasher take a look at the Lanebreaker. Same line, redesigned core, slightly weaker cover. Comes polished but put a little surface on it, and it might be just want she's looking for. Even polished it reads the midlane very well, as it has a little bit lower RG and slightly higher diff, getting it to rev up a bit quicker.
Hope this helps