Man, you even said that in your credits:
* Thanks to XARIUS for 1v1 Knife Fight plugin till version 1.2.1
http://forums.alliedmods.net/showthread.php?t=77948
So I guess you just fix some minor problems in that plugin and thats all.
Why claim it yours then? You could post that in that plugin forum and thats it...
You even copied the same intro from that plugin