As I fought through the various creatures of the nether, my armor got beat up and then broke. What broke with it was my new diamond sword with unbreaking on it. So I was fighting blazes, and they were close enough to hit me, so I tried blocking their attacks. As I was blocking, I got hit, my chestplate broke and my diamond sword disappeared from my hand. Today the same thing happened today twice. In the first instance I was fighting a wither skeleton with a fairly new iron sword, a piece of armor broke and my sword disappeared again. Then without a sword, I had only a bow, so as I was drawing the bow back to shoot some blazes, one of their fireballs destroyed a piece of my armor, and the bow disappeared. At this point I knew it was a bug.