Constellations lore

[Kaiser-Ace]

Celestial... Bahamut... Fire... Nidhogg... Lightning... Timat... Wind... Hmmm.

That almost makrs a scary amount of sence.

7 Dragons, 7 Constelations, 7 Eorzian Elements.

We know that the seventh Eorzian heaven is only achivable via physical death so the 7th and final element could be nullity as Oha-sok's name is the Elemental of Nullity.

The meaning of Nullity being "of no use/meaning" commonly used to describe Nutrality.
So I perpose Hrasvelger=Wind, Nidhog=Fire, Ratatoskr=Thunder, Tiamat=Water, and Bahamut=Nullity.

The basis for the last three being Tiamat js ocationally the Arcfiend of Water, Lightning Crystals apear near where Ratatoskr was killed, and Bahamut being traditionally non elemental. Thus leaving only the Earth Dragon unacounted for.

[WyrahFhurrst]

That almost makrs a scary amount of sence.

7 Dragons, 7 Constelations, 7 Eorzian Elements.

We know that the seventh Eorzian heaven is only achivable via physical death so the 7th and final element could be nullity as Oha-sok's name is the Elemental of Nullity.

The meaning of Nullity being "of no use/meaning" commonly used to describe Nutrality.
So I perpose Hrasvelger=Wind, Nidhog=Fire, Ratatoskr=Thunder, Tiamat=Water, and Bahamut=Nullity.

The basis for the last three being Tiamat js ocationally the Arcfiend of Water, Lightning Crystals apear near where Ratatoskr was killed, and Bahamut being traditionally non elemental. Thus leaving only the Earth Dragon unacounted for.

6 constellations for the 6 elements. Sorry if that pokes a hole in the theory.

[iiroro]

7 Dragons, 7 Constelations, 7 Eorzian Elements.

The basis for the last three being Tiamat js ocationally the Arcfiend of Water, Lightning Crystals apear near where Ratatoskr was killed, and Bahamut being traditionally non elemental. Thus leaving only the Earth Dragon unacounted for.

For the 7 Constellations, or the Heavens, there are also 7 corresponding Hells.

As for your speculation with the dragons, you have forgotten Ice. I agree that Hraesvelgr is possibly associated with Wind, as in Norse mythos he is a giant who shape shifts into an eagle, but he's elemental affinity may instead be Ice. My reasoning is mostly because his association with Saint Shiva (Shiva always being represented as the Ice Summon in the FF franchise), and to a superficial extent he's white...

I'm also not sure if Ratatoskr's elemental affinity is Lightning, again going back to the Norse mythos, Ratatoskr is a squirrel and the only squirrels I know with Lightning powers are in Smite and Pokémon.