Hello,
Could you help me please? Is there a way to disable the blur effect that happens when you get hit in melee?

I looked through all of the console commands and tried several, but they had no effect. I did the same with the config file.

I also looked for mods, but couldn't find any that address this.

The developers probably hard coded it (meaning it can't be changed with a config file or console command).

If there's a solution, I can't find it.

If you want to give it a shot yourself, here's a list of the console commands:
http://pkzone.org/downloads/configs/commandslist/

I know is too late, but will be useful if someone search for it.

Here is a guide/mod that i've made for this:

Only latest Painkiller have a blur effect; for all other PK games disable bloom option