Good thing nothing was taken. Oh my poor bag, I got it as a gift from my sister, and now it's seems beyond repair. It's Gap by the way, though it's quite cheap, but I love it. So, I'm just gonna keep it. And at least it was only the bag he slashed, and not me. I will just let karma do its stuff for that man.
Advice for everyone: Be very careful with your bag/possessions when riding on public transportation. Always watch your handbag.