Editing .C3 files?

How can I edit these files? I have photoshop, if there is just a plugin i need to download?

I want to edit my gold guard to be invisible. more importantly I want to edit its health bar to be invisible (although im not sure if this is possible because maybe they all use the same health bar file? so it would ruin monsters as well?) If anyone could point me in the right direction it would be helpful, Even if editing the guard or its health bar has nothing to do with the C3 files I would still like to know. Thanks for any help!:)

To make a guard invisible you can just edit the .dds file for it. C3 files are the 3d wireframe models that textures are applied to.
Health bar isn't in any texture, it's code-generated. Health bars show up for any entity that has an ID within a certain range (100,000-1,000,000 or something like). This includes guards. If you wanna get rid of the health bar you'd need to somehow spoof the ID of the guard using memory edits or modifying network packets, neither of which is a simple task.