Something like Chivalry: Medieval Warfare ? Screenshot 3/21 has a good image but I wont link the image specifically because of the graphic content (limbs missing).
The answer to your question depends a lot on if it’s single player or networked. You can dumb down the requirements if not networked, but I’ll answer as if it is.
I’ve never made this system but I can see quite clearly how I would.
- Model a proxy character that everyone else sees - the full body. This proxy would have a proxy weapon model as well.
- Rig the character and make sure there is a joint for the weapon.
- Model a high res version of the character’s arms and weapon with near identical proportions but more detail.
- Rig the arms, ideally using the exact same joint locations as used for the proxy character model. You want animations to align perfectly.
- Animate the proxy character for attacking such as a sword swing.
- Apply this animation to the high res arms + weapon. Add detail but maintain the basic movements so they align.
- Camera would be from the head but you might adjust/offset it a bit for where it looks better but without moving it too far from the head.
- Make an animation instance for the proxy character. Attach weapon to socket.
- Here I’d have to toy with things to figure out the best method, but ultimately when the proxy plays an attack animation the arms/weapon that the player sees need to do this also.
So, in summary: Have a lower res full body character + weapon that everyone except the player sees, then have a high res arms + weapon that only the player sees. Animations need to look great from first person while still looking good in third.