I would second that the NRS-2 looks similar to this one, but based on color, and handle styling in what limited elements are available. This is also likely a fictional weapon blended from or inspired from multiple things which would kind of make sense given the narrative of the story. Little elements like the fact that the sort of T shape elements that would make a sort of little wristguard there, are offset like the one on the blade's a little lower which is more indicative of a foldout model with a lock. Like the kind Smith and Wesson makes. You can also see how it's got a hard edge there like that part might pull back and fold in. Sort of like this guy and it also shares a super defined single edge with a blackened blade, which is closer to lots of American combat knife companies, like SOG or again S&W. Either way most of the stuff in Honkai is just super cool looking so if there is a perfect replica, I hope someone posts a link to it.
Hm. So far the Kershaw Freefall seems like a good choice for me. I also like this knife, but it is a bit expensive.
I'm just here as a fangirl, but this Smith and Wesson M&P https://www.amazon.com/Smith-Wesson-SWMP4LBS-Stainless-Assisted/dp/B002OAU30G has served me well for many years.
I got it from Amazon
I use the Smith & Wesson SWMP4LS M&P It is a great knife. It is my EDC.
https://www.amazon.com/gp/product/B002OAU30G/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1