Convert unit ability to civ trait?

[Ghiaman1334]

I was thinking of using the Varu's defense debuff ability as a civ trait, i.e. enemy units lose 5 military strength against any of my units, only when they attack me (or maybe the other way, if I attack them). I know it seems OP but I could tone it down to about 3 MS. I have found all the code for the Varu, but I wanna know, what should I do to it to turn it from linked to the unit to linked to the civ? I'm new at this, so I don't know immediately.

 

[Ghiaman1334]

Development: I've worked out that, with a little fiddling, I can attempt to combine the Varu, Beserker and Roosevelt Corollary to have the desired effect: the Varu is for reduction near unit, Beserker for damage reduction when defending (change defend to attack), Roosevelt Corollary for tying it to Civ rather than to unit.
I'm learning. Still need help.