Basically title. I'm a shield master who frequently uses his shield to slam people down prone. I want to minimize my chances of having my shield taken away from me.
Jeremy Crawford states something interesting from his twitter below:
@dpnorton If you attack with a shield, it's a normal improvised weapon, unless a special feature says otherwise. @SeldenNeil
— Jeremy Crawford (@JeremyECrawford) February 13, 2015
Also, the link below is extremely ambiguous, but Jeremy basically states that EKs can "use" shields and 2-handed weapons in the context of weapon bond (See the "weapon bond" tag below tweet):