I like [THIS] idea about player hold the shield,

seem I'm not good at coding, so there are a lot of different things :

• your primary must be Akimbo (Thanks @Mxswat for giving this idea)
  
• when you use secondary or melee, your will put down the shield.
  
• any bullet damage is decreased when you have shield and face to it.
  
• this is not synced to other clients.
  

Preview :
https://goo.gl/o3UcBi