Hi, I’m currently making a RPG game that would have a vast world, and also a great deal of armors. Do I have to design a special model for every new armor or is it possible to “slip” them on? I recall from my time modding TES IV : Oblivion that armors could slip on any model, as long as there aren’t any clipping issues etc. Is this the same case here?
Please keep in mind that I just started Unity, so please thoroughly explain 
Thanks in advance!
Yes, it’s possible.
There are three ways to do it.
The good thing about #1 is that it’s easy and armors can always be expanded. Bad thing is it doesn’t work for animated parts such as fingers. Perfect for things like shoulder pieces, bracers, boots(only if there’s no toe animation) shin guards, helmets, anything that doesn’t need to be deformed.
Good thing about #2 is… well… everything. It’s the best way although if you’re developing for mobile it will be slightly more taxing on the polygons. It’s like 1 line in a shader to clip the hidden ones though.
The other problem is you’ll need a devoted and/or paid animator who will bake the animations on to any new armor pieces you have. Also it can get kind of messy if you come out with a new race or something and you’d want to re-use the armors with different animations.
Good thing about #3 is it’s also easy and can still be decent quality with normal maps, but ultimately it will always be the same mesh. All that’s required of this is to set up UV maps in a 3d modeling program.
Basically 90% of the work of what you want to do is done in 3d modeling software. In Unity all that’s required is parent the bone to the object, stuff like that.