Full patch notes are here

[Rhas]

You're reading it wrong. Bolded the relevant portion. It just means you don't have to buy a 3rd retainer on each individual character. Charcter 1's 3rd retainer is still separate from Character 2's 3rd retainer, just like their first 2 retainers are.

Which can also be read (since they have the option) of multiple character accounts and single character accounts per server.

It's still good to dream ;P