>>530367327
If you think of sparkle as an external archer eidolon, she's not bad. Sparkle gives archer more of a % boost than his eidolons and she has a chance of getting buffs in the future.
It's not clear if they will buff true limited characters so adding the gold to archer's main body directly may have worse long-term returns.
It's best to wait for cerydra v3 and more dan heng III kit crumbs before doing anything though because cerydra might be better, or e0s1 sunday might be stronger if dan can add a summon to archer.