I use this thing called ".minerva", really handy but not always I guess.
For the effects, according to .minerva, well you can't use .minerva to add stuff, I just figured that out, but how it works, I can only describe it as;
It has this thing, that in .minerva it is a cyan A that says "effects", in which you can tab out and numbers from 0 to probably infinite (at least 3 is the max I could find) come out. These numbers are named as S, and they're green. If you click on them, you'll get a text which depends what kind of effect it has. For example, if the weapon has +30% Accuracy, it would be "accuracyMore".
With .minerva, I can modify it, like if I don't want "burnChance" (Since my Merc has that badass feature already) then I can change that to "accuracyMore". But as I said before, I can't add it.
So, even if I don't really have like a good proof about it, I am somehow very sure that you can add these effects on the weapons yourself, at least from 0 to 2 (which is three effects max).
Is that information good enough or you might require more?
Edit: P.S (Off-topic) Tsumi, put one more hack and get 69 hack count, I'll think you're a total badass. Unless you hate being appreciated.
Hating the Soviet Union since 1924.