I have a couple of attuned heritage items. Since attuneable items are freely tradeable, and you can't put attuned heritage items in your shared bank, why have items marked as attuneable heritage?
Attuneable Heirloom is a flag pair that works exactly as designed. When the item drops and you loot it, you can move it around your account via the shared bank. Once you equip the item and attune it, it becomes Attuned, which makes it untradeable and nontransferable via the shared bank. Thus the point is you can give an Attuneable Heirloom to a different character on your account, but once you equip it only that character can use it (unless you get and use an unattuner).
The point is that attuneable items are freely tradeable anyway, including via your shared bank. So making them Heirloom makes no sense.
It makes total sense. You can trade them among your own characters on the same account until you attune them. They can't be given ( or sold) to other people on different accounts at all. If they were just attuneable, they could be transferred to people on other accounts. If they were just heirloom, they could be transferred to any toon on your account at any time, even after they had been used for a while on one toon. With heirloom attuneable, you have to pick which toon you want it on, ad that the one it's stuck to. (Well, unless you have an item un-attuner.) (which, after I posted it, I noticed is almost word for word what Lordebon said. ) Some things you just can't give to other people after you pick them up.