Most mobs with CanPickUpLoot prefer swords over axes and will downgrade their weapon

Steps:

1. Summon vindicator with command

   /summon vindicator ~ ~ ~ {CanPickUpLoot:1b,HandItems:[{id:iron_axe,Count:1},{}]}
   

2. Drop wooden sword
3. Vindicator will downgrade his good weapon to a worse weapon. Afterwards will only upgrade to better swords