Oh yeah that's definitely a real feature in the base game! You'll need to get into the reflexes skill tree first since that's where all the blade-related perks live. The key is maxing out lead and steel, which needs 9 points in reflexes, and then picking up bullet deflect right after that.

What's really interesting is that both katanas and mantis blades can do this since they're considered blade weapons. The way it works is pretty straightforward - once you've got the perks, just keep your stamina above 33% and you can actually deflect incoming bullets right back at enemies. If you time your blocks just right, you'll even deal extra damage which is pretty sweet.

Just a heads up though, some people have mentioned the mantis blades can be a bit finicky with deflection sometimes. It seems to work fine most of the time but occasionally the animations might not play nice. Katanas tend to be more reliable if you're really wanting to lean into the whole bullet-deflecting playstyle. You might want to look into some stamina management cyberware too, since blocking does eat up your stamina pretty quick. And if you combine it with stuff like bullet time later on, you can get really creative with how you handle firefights.