I was updating my linkshell site and forums with new database information and happened to think about these items.
====[Odin Choices]====
Aesir Ear Pendant
[Ear] All Races
Attack+7 "Conserve TP"+3 Dark weather: "Conserve TP"+6
LV 75 All Jobs
Aesir Torque
[Neck] All Races
+20 Elemental magic skill +7 Dark magic skill +7 On Darksdays: Elemental magic skill +10 Dark magic skill +10
LV 75 All Jobs
Aesir Mantle
[Back] All Races
DEF:6 Attack+8 "Double Attack"+1% On Darksdays: "Double Attack"+2%
LV 75 All Jobs
10,000 gil
====[Alexander Choices]====
Colossus's Earring
[Ear] All Races
HP+10 MP+10 Physical damage taken -1% Light weather: Physical damage taken -2%
LV 75 All Jobs
Colossus's Torque
[Neck] All Races
+20 Healing magic skill +7 Enhancing magic skill +7 On Lightsdays: Healing magic skill +10 Enhancing magic skill +10
LV 75 All Jobs
Colossus's Mantle
[Back] All Races
DEF:5 HP+20 MP+20 Magic damage taken -2% On Lightsdays: Magic damage taken -3%
LV 75 All Jobs
10,000 gil
Also from what i could gather these are the quests:
Waking the Colossus Client: Nashmeira
(Throne Room, Imperial Ward)
Summary:
Curious readings from the chamber
where the iron colossus sleeps have
Imperial researchers ill at ease. At Her
Majesty's behest, seek the support of
the four nations for a plan to repair
the colossus and free the Empire from
its shadow once and for all.
Divine Interference Client: Nashmeira
(Throne Room, Imperial Ward)
Summary:
The avatar of Alexander once again
threatens to force its way through the
spatial distortion in Nyzul. Procure a
replacement power source from the
Moblin Megomak and reactivate the
colossus to send the extradimensional
intruder back whence it came.
The Rider Cometh Client: Nashmeira
(Throne Room, Imperial Ward)
Summary:
Ominous rumors circulating among the
mercenary ranks speak of Dark Rider
sightings deep within the Hazhalm
Testing Grounds. Could this
occurrence bear any connection to
the unsealed spatial distortion? It
falls to you to investigate.
Unwavering Resolve Client: Nashmeira
(Throne Room, Imperial Ward)
Summary:
Ghatsad aims to seal the distortion
that is the Dark Rider's portal into
this world. You must procure another
key and return to Hazhalm to collect
the data he seeks. Meanwhile, Ovjang
and Mnejing would ask of you a favor
of their own...
A Stygian Pact Client: Nashmeira
(Throne Room, Imperial Ward)
Summary:
To reclaim the soul of Prince Luzaf,
you have have entered an unholy
covenant with the Dark Divinity. What
trials await you as Odin's knight?
Shrink not from the shadows, and be
strong in your convictions, that you
might emerge unscathed!
How these quests relate and exact steps obviously nobody knows just yet.. could be updated at a later time or if someone replies with good info i'll gladly update the OP
Also it has NEVER been specifically said to my knowledge that these items are 100% for sure from the respective prime battles. It just stands to common sense with the tradition of things so i used my noggin to assume this information is fairly correct. (AKA you can't internetwisesueme :P)
Sources: http://ffxi.allakhazam.com/forum.html?forum=10&mid=1269276307226732316&num=182&page=1
http://www.bluegartrls.com/forum/showthread.php?t=90667