Ok so I was on creative mode and I was experimenting to see what items mobs could pick up. I tried giving a baby zombie a diamond sword and I noticed that it didn’t look right. 

Steps to reproduce:

1. Type the command: /summon zombie minecraft:as_baby (hope this is correct)
2. throw a diamond sword at it (or any other sword)
3. it should pick it up. 
4. it doesn’t render correctly.