Classes?

[linay]

It is so that there are no issues if the job stone winds up unequipped somehow.

This is precisely one kind of "training wheel" (to use a term from another thread) that could help ensure you unlock your job and keep it.

if you happen to have a retainer that isn't a job you can equip that gear on them if they are still ACN/THM/etc.

Time for retainers to upgrade as well.