In the patch notes says:

Additional retainers can be purchased via Optional Services.
Players may purchase up to two additional retainers. The purchase of an additional retainer will apply to all characters on a single account. However, a single retainer cannot be shared between characters on a single service account.

What exactly this means?
That no retainers can bet shared between characters?
or that they will allow retainers share except for a single retainer?
I guess something is odd. It must had lost some meaning in the translation from japanese.