It will be 10 years since AL launch this year. It would be nice to reward veteran players who have 10/5 years old accounts. Something like you did with those backpack vanities back then.

But please keep in mind that some veterans play hardcore now and would like to get those exclusive rewards on their hardcore toons so usual way to distribute it via stash will not work. Maybe add some special NPC or pack for 1 gold in the store or something else that would work for hardcore toons.