New Legendary Weapons
A livestream will be showcasing the new Legendary weapons sometime between now and HoT launch.
New Legendaries and their precursors will be account bound. Legendary backpack/armor will also be account bound so you have to play the content to get them.
Legendary Crafting Mastery
This will give you an account bound precursor. The legendary crafting from precursor to legendary step is not being changed.
You will need to unlock the Legendary Crafting Mastery line to be able to purchase these volumes that allow you to start off the precursor crafting collections.You need to progress down the Mastery line to able to get the 2nd vol and third vol etc.