How the Warlords of Draenor legendary quest line rewards should have worked?

With patch 6.1, Blizzard introduced a new heirloom system to keep track of the various items you find that you can use while levelling that scale with the level of characters. It supports upgrades and keeps the upgrade progress on an account wide level. Upgrades are done by buying an item and using it on the heirloom in the heirloom …