Each weapon must be treated differently.
What I would do:
1] Load my mod on Corsix.
2] Start browsing the weapon list and modifying by hand, ONLY the weapons that require my special attention. This will take some time, but I suppose the vast bulk of weapons fall into the "generic" macro-category.
3] Once done with the manual changes, I would quit Corsix, get into the weapons folder (windows) in attrib, sort the list based on date of change, REMOVE (cut, and paste elsewhere, temporarily) the weapons I modified, and thus leave only those that fall into the generic category.
4] Re-run Corsix, and NOW apply the macro. It will only affect the weapons I left there
5] Re-put the weapons I previously removed, into the weapons folder.
This ides is OK, under the presumption that the ruled-out weapons (those that I would have to modify by-hand), are just a handful.
And that the remaining (that the macros should modify), are like 90% of the total.
If they are like 50-50, but you CAN STILL think of a formula that "filters" specific stats of MOST weapons (leaving out only a few exceptions) and make the changes, this would also work. It would increase the complexity of the Macro, but this is really insignificant.