Simple script, not done before. As you expect (title is really obvious), with this script you will be able to throw your knife and damage or kill your enemy.
If friendly fire is off, you won't damage yourself and your teammates. If ff is on, you will. You can change damage per hit. 75 by default. You can change if your knife is stripped, when you throw it. It's true by default (you'll lose your knife). What Yates said. I tested and weapon won't be stripped from player, if it's his only weapon.
I get inspirated by Livia's object method of treating players( Extending native functions) and I made similar one. This script needs my ObjectPlayer.lua to work!
How to install this script? Just unpack zip file to your sys/lua/autorun folder
Does it still throw the knife if that is the only weapon in your inventory? If it does, disable that. Stripping knife with no other weapon will lead to weird bugs.