This has been my main set of gear since the end of Stormblood, once the Scion Traveler's Boots were distributed through the MSQ quests. The Holy Rainbow set of gear can be crafted but the shirt is basically the most important part of it.
I imagine this as being an appearance that a main cast Final Fantasy character would have were they introduced in any of the other mainline games.
The set works perfectly for all roles as there are multiple variations of the Holy Rainbow shirts.