Why is my edited arz so much smaller than original?

Theres a mod I just wanted to edit the value of one skill for my personal use.

I extracted the base game, and two expansion game files in asset manager.
I extracted the mods .arz file.
I found (what I think) is the file in question. (Pet skill)
I edited the value
I built the mod in asset manager.

No errors during the build. I literally only edited one value, and the rebuilt mod is 7 megabytes smaller than original

When I try running the mod, the custom skill trees and icons are completely gone.

Any thoughts?

If you start with an existing mod, you need to have all its .dbrs in your mod’s database folder, otherwise they are not added to your mod.

Keep the .arc files of that mod (since you made no changes to them). Chances are you do not have asset files for everything in them, which is why the skill icons etc are now missing

so because I don’t have the original assets, even if I keep the same .arc files, the mod will be incomplete? ie impossible for me to mod?

When I try running the mod, I use my new .arz, and the old unmodified .arc

No, you have to keep the original .arc files rather than use the ones AssetManager creates for your mod.

If you do that and still have issues, you screwed up the .arz somehow.