No, there are no ways to make weapon mods specific to the player only. But you could drop the health from the insane number to a semi-large one.
I'm sorry to hear that some still can't get it to work, for me and a few buddies it seems to work just fine when you play on a local, or silver or no account. No matter what version of Live you have. You have to remember that there are two binaries folders, the one in the account folder, and the game folder- where it should be- with the .exe files, and I can't recall, but the commands might be case-sensitive, so when you enter the "exec Mod.txt" it sould look like that, but without the quotes.
And you should only enter the command when you are in control of the character and in the beginning of new chapters (effects still carry out in the rest of the maps, but sometimes, like the weapons you get later, are not loaded into all maps, so after you get a new one, enter it again and the effect should stay for the rest of the session)
Here's a link to the file itself:
Might be some new mods, can't remember anymore, should be simple to notice. Just save it into your GoW binaries folder, like I've said somewhere a few pages earlier.
[Edited by Caboose666, 6/13/2009 12:54:19 PM]