Got it, thanks. I've just created my first mod, which was an attempt to eliminate the damage bonus of Cuman Killer to effectively erase the perk. I changed the "wat" value from *2 to *1, but left "bad" at 0.5. However, nothing seems to have changed, and Cumans are just as easy to kill as before. If you'd care to maybe take a look and tell me where I went wrong, I'd very much appreciate it.
I edited the file in Notepad++. Also, instead of creating a new directory with Libs and Tables, I simply deleted everything but Libs and Tables in an existing directory after extracting Tables.pak. I also deleted everything but "buff.XML" and I also deleted "buff.tbl" and created an empty text file with the same name. It looks just like any other mod I've seen, so I have no idea why it's not working.