Modding

Hello.
As far as I understand, most modding questions are asked here. My problem is as follows:
I've more or less learned how to modify creatures; I can change their stats, cost, experience, and their abilities (both passive and active). The problem lies in the latter.
Is there a way to change the ability itself? For example, I want to change the "Weakening Strike" ability of the Plague Zombies. I find it in the game files, open it, and see that there's nothing special in the file. The file references the name and description of the ability, as well as the effects and icon of the "Weakness" spell. There are also application specifics (e.g., it applies to enemies, on hit, etc.). But I didn't find any "characteristics" of the ability itself, and it doesn't even reference the Weakness spell in any way.
So, the question is: is it possible to change this ability?

I would like to ask everyone who knows about modding: how do I create a 3D model of a creature for HOMM 5 ToE, or rather for HOMM 5 EWA? Maybe there's a program for creating 3D models? :confused: I just want to create cool and awesome creatures for the game. Like the Creeper from Minecraft. :D