The bug

Mobs ignore the attack speed of an item when they attack with it. This can cause pretty big problems if you have an item with a high attack damage but a very low attack speed, which is therefore balanced for players, and somehow a mob picks it up.

How to reproduce

1. Give yourself an item with a high attack damage but a low attack speed

   /give @p diamond_axe 1 0 {AttributeModifiers:[{AttributeName:generic.attackSpeed,Name:a,UUIDLeast:1L,UUIDMost:1L,Amount:-10.0,Slot:mainhand},{AttributeName:generic.attackDamage,Name:a,UUIDLeast:1L,UUIDMost:2L,Amount:50.0,Slot:mainhand}]}
   

2. Summon a husk, which has like a player a health value of 20

   /summon husk
   

3. Try to kill the husk with the axe
   → It should require two hits
4. Equip diamond armor
5. Summon a husk with the same axe

   /summon husk ~ ~1 ~ {HandItems:[{id:diamond_axe,Count:1b,tag:{AttributeModifiers:[{AttributeName:generic.attackSpeed,Name:a,UUIDLeast:1L,UUIDMost:1L,Amount:-10.0,Slot:mainhand},{AttributeName:generic.attackDamage,Name:a,UUIDLeast:1L,UUIDMost:2L,Amount:50.0,Slot:mainhand}]}}]}
   

6. Switch to Survival or Adventure mode and let the husk hit you
   → You are instantly dead