During my time on the project until I left, I was in charge of all the weapons and items.
I made a weapon LUA system that handled all the weapons and items, and I scripted their behavior, a barrel burning, reload smoke, bullet shells, the flare different behaviors, up, floor, takedown.
Apart of the scripting, I also worked on all the textures and particles systems. For what I saw my version got quite preserved in the shipped product.
I also made all the bullet impacts decals and textures and meshes from scratch for this project to look more realistic using photo-scanning and substance designer, for that I used the Decal manager and Contact Manager Scripted by Daniel to set it up, they look the same than when I left but sparks where added to a lot of them for some reason.
For the Blood Impacts, I scripted a custom behavior depending if was a headshot or we impacted a limp. I also made different decals depending on the distance to the wall and the part of the body you hit. If you are close would be denser, meanwhile if its far would spawn a more spray type of decal.

I also added brain pieces that slide on the wall if you made a headshot and made a decal more dense with some debris. The final iteration of the blood particle VFX is quite different of my version, still use some of the content I made but become bigger and the albedo changed to a more bright color. Damian Olechowski made the wound system on the enemies
I also made the first iterations for some of the enemy attacks like the tank, thrower and normal enemy slash and setup their impulse wave.
As far as I know Matthi, Jose, Elina and John took over the final passes, bug fixes and tweaks of all this.
Lead VFX:
https://www.artstation.com/richterteer
Team
https://www.artstation.com/doosead
https://www.artstation.com/dam
https://www.artstation.com/mckennafx
https://www.artstation.com/elineslingerland
https://www.artstation.com/josemorval
https://www.artstation.com/isacstahl