-Make the forlorn lady thing which grants bonus XP to appear in ARR and HW fates as well.
-Be able to keep the buff when changing zones - I can see how this could be exploited though, so maybe make the buff only apply to fates of the same level range to avoid someone getting the buff from ARR and jumping to ShB.
-Some form of reward outside XP, like random item drops, reputation currency, temporary stat buffs or maybe even a minuscule amount of tomes.
-More "world boss" type of fates like Odin and/or make them be worth to hunt more than once and done. (I don't think people even did the Tempest or Kholusia ones anymore after the first 2 months, same with Ixion or Fox Lady)