I believe the question is.
How do you share items with characters on the same account?
If account sharing is not a possible thing, then why bother mentioning if an item can be shared by characters on the same account. The only method of "sharing" I am aware of is mailing things between your characters, which costs money to do and I'm pretty sure is something you can do with anyone. (I haven't tested it, but I'm sure you can send anyone random items in the mail)
You can (I think) share items if you throw all your characters into the same guild. But this will require you to trust someone else to invite each your characters to said guild because a character needs to be online in order to be invited to a guild. AND you need to level said guild enough to unlock the guild storage.