Not entirely true, butscrew. Someone could still model a shuriken as a throwing weapon, and I'm sure that NPCs that turn into enemies when they see you/talk to you (Custom Settlements) wouldn't be impossible to code, so assassination missions aren't out of reach either. But as far as I know, there ain't such a mod out there. And like butscrew said, it probably wouldn't be a very fun one, given the game mechanics of M&B.