You know, I was actually thinking about something similar with Genshin's constellations in mind. In Genshin, getting duplicates of a character unlocks new perks that are generally flat upgrades to your character.
Here are some images of what that looks like:
What if instead of getting 1 new action or trait at levels 92, 94, 96, 98, and 100, you instead have something like this, but instead of 1 option, each level is associated with two similar perks, and you have to choose only 1 of them. The menu would look kinda like this:
Each side would have a theme. For White Mage, this could be the Astral path and the Umbral path. The top two icons linked are what you get at level 92. So let's say those effects look like this:
Umbral Path: Mhachi Light
Increases the potency of Glare III by 10, increases the potency of Afflatus Misery by 40, and increases the potency of Dia's damage over time effect by 5.
Astral Path: Floral Force
Decreases the potency of Glare III by 10 and the potency of Afflatus Misery by 40, and unlocks the use of the action
Tempest.
Tempest: Deals unaspected damage to the target and all enemies nearby it with a potency of 510 for the first enemy and 40% less for all remaining enemies. Each time a lily is added to the Healing Gauge, enables 1 use of Tempest.
The Umbral Path is easier and offers a smaller damage variance based on performance while the Astral Path creates more room to optimize and thus has a slightly higher high but also a lower low, and your performance makes a bigger difference. The difference in these two options, if my math is correct, is the Umbral Path is a potential gain of 340 damage per minute if every GCD is used on damage or lily heals while the Astral path is a gain of 360 per minute if every GCD is used on damage or lily heals, but also gets a little more out of buffs this way as well. The difference is small, but the player has an easier path or a harder path. This kind of system would hopefully allow the design team to give healers a more aggressive route without worrying about scaring away the novice healers since they can just take the easy road.