Relative power scale of spells?

During my A12 spam earlier I just thought of something. Given the English translation giving spells a relative power (acquisition?) level, such as Fire 3 and Fire 4, where do all the variants of Holy fit in?

White Mages have access to "Holy"
Knights of the Round use "Holiest of Holies"
Alexander Prime uses "Mega Holy"
Guardian Wings use "Almost Holy"

So in a theoretical "holy-off", which one wins?

On a similar note, how do the "Void" and "Dark" elemental spells fit in power-wise relative to the Black Mage's arsenal?

Don't forget Pom Holy, Unholy, and Ancient Holy!

A lot of the time, these are just meant to differentiate the spell "Eorzeans" are using from the spells enemies are using (or sometimes to mitigate the 500 versions of Holy in the back-end files, I assume).

Sometimes, these names are pulled directly from the franchise history related to that mob. Alexander used Mega Holy in FFXI, for example.

Who would win in a Holy-off, that I can't say. After all, these seem to be horizontally different but ultimately comparable spells cast by beings of different comparative power. Plot-wise it's hard to beat Alexander, but here he (like Thordan) is a primal, so the strength is dependent on aether and prayer...

As for the Void Xs, I'd say equal. Void Fire is equal to Fire and so on. Sometimes you might have to translate a suffix to a number, perhaps.

I don't know, "Dark Fire III" visually resembles Flare and inflicts Burn status (which Fire III does not do).

It's probably dependent on the individual's power level. It's extremely uncommon to see something beyond the basic "Holy," since it's typically the offensive White Magic. The name variations are more than likely there as the spells are all variations on the basic "Holy."

Alexander Prime's Mega Holy is probably the most powerful, relatively speaking. He is the soul of a sentient magitek steam colossus... who can manipulate time... and use holy magic on top of all that...

isn't the "Number scale" for Fire/Ice/Earth/Wind spells only cause NA localization team believed we would have trouble telling the diff between a Fire spell & a Fira/Firaga spell (like they are in most other FF games)? that aside I'd go with the assumption power of welder casting it has some sembolance on its STR (Fire 3 from a novice could be as strong as fire 1 from a master)

The Ixals have their own Ixali Aeros

From what I understand spell names are named in order to distinguish distinct spells and their variations.

• Holy is a Light/Astral spell first used by the White Mages of Amdapor
  Ancient (spell name) is an older version of a spell used prior to the development of modern versions in the 4th Astral Era. Power seems to be slightly more powerful than the common versions.
• Mega/Giga/Tera (spell name) are more powerful/scaled up versions of spells used by some Primals/Eikons and those they are empowering. Currently we have only seen versions of Flare (used by Bahamut Prime) and Holy (used by Alexander Prime).
• Almost (spell name) are scaled down versions of the Mega spells and used by secondary creatures summoned by some Primals. Almost holy is the only version we have seen.
• Holiest of Holies is a weaponized version of Flash using Light/Astral aether exclusively. Could technically be called Holy Flash.

• Dark (Element) refers to distinct spells that admix Umbrally attuned aether with an Element. Stronger Voidsent tend to use various Dark Fire and Dark Blizzard spells.
• Holy (Element) refers to distinct spells that admix Astrally attuned aether with an element. Many of the spells used by the Heavens Ward are this sort of spell.
• (Beast tribe) (Element) are distinct versions of spells developed by members of various beast tribes. The Ixali's Aero series and the Moogles' Pom (Element) series are examples of these.