You can't just add random objects to the player models, they have to all follow the same bipedal structure, using the same amount of bones and objects within the bones. The animation you have here would not work in GunZ, it just wouldn't. Animations are read one at a time, not added upon each other and harmonize with one another. If you plan on having wings, you would have to develop every single animation (~30) in which had these wings. If you wanted 2 dozen feathers, well you better plan on having 2 dozen feathers when you start making your first walk animation as well.
Mesh names inside the model file are important and only one can be used per armour piece with the exception of an avatar. As for animations with weapons, unless you wish to do a total rehaul of the engine itself, the only animation available are created by texture animations or are hard coded.
The only animations that can be really done completely and totally free of parameters set by MAIET are new NPCs and map assets.
Developers are messing with these things, we just don't give out freebies every chance available, heu heu heu heu. (If you want to know the truth, I have RealSpace 2.0, RealSpace 3.0, and the Eclipse engine completely documented which I performed nearly entirely myself, if that isn't "messing with these things" idk what is.)