So, in-game, there are these big, bold outlines around the models, and I was wondering if you could take them off.
Help is much appreciated.

They are disabled when the shaders are on.
Currently there is no way to disable it manually.
Hmm.. you can post a suggestion for it in the suggestions thread.
I think that they were added to easily distinguish between the characters and the white background.

and btw, they are helpfull with swords, cause when you have shaders on, the swords are very hard to see, cause they're white, and thin...

There should be a launch option to use (Kind of like -hud 0) for rendering shots/videos for movies/images.