I feel like they could write Taric in to Demacia properly, since right now he's kinda just plonked there. They just brought out the new items Crystalline Bracer
and Righteous Glory
, both of which look pretty Demacian to me (They look like Garen's armor), and have connections with gems, in their aesthetic and their build paths. While that may be a bit of a stretch, it could be that Demacia can utilize crystals and gems as a medium for magic, and that Taric, being a "Gem Knight", is one who is well versed in the ways of crystal magic, allowing him to wield immense divine power using it.
Keep in mind I thought this up mainly because of these two items, Garen's armor aesthetic and the gems within his armor, and Taric's current status as being plonked in Demacia. Could be total bollocks! But I feel like it could be a cool idea, I mean, it would explain where Garen gets the power to bring down a sword of light upon enemies, its in the gems!
"More than just stones, I bring you an ancient power."
Is that ancient power the origin of Demacian justice?! I dunno. Just speculating!