Okay I'd figure I'd try to make a list of the gear that is specifically Allagan one way or another. So far I got
Some more ambiguous cases (as in whether or not they're canon and if they originated from Allag)
- Evoker's Attire: Traditional garb made by their Summoners
- The Veil of Wiyu: Again due to Summoners starting in Allag. Notable for the wilder being related to Odin
- Duel Haken: Moenbryda's Axe, reveled to be an Allagan weapon in the Encyclopaedia Eorzea
- Onion, Crimson, Royal, Fuma, and Ballad gear and the Armor of Light: Found on CT and specifically worn by exhibits in the Fractal Continuum
- Allagan and High Allagan gear: the hint is in the name :P
- Caller's Attire: Create around the heyday of the Summoners, when they were considered Heroes in Allag
- The Almandal: Also Allagan in origin, The cover was designed with aspects of the original Owner's egi in mind.
- Peacemaker: Another Rowena's Token Weapon. This was also revealed to be an Allagan relic (it certain seem garish enough for it IMO, especially compared to the Almandal and the Crystal Tower Gear)
Gear that can be found related to Allag but I think did not originate there
- Dreadwyrm Gear: Put simply I think the gear was not made by Allag but by Bahamut (somehow) assuming that it is like the Sycrus gear in that it doesn't actually exist
- Adamantite i150 Gear. On the one hand it is possible Gerolt and Rowena based the Masterworks on this gear given the Tomestones and the "information currency" system the House of Splendors set up
- Primal Focus Weapons: It seems that given the precedence of the peacemaker and the Dual Haken being confirmed Allagan Relics, I cna speculate that the other i90 weapons from the House might also be simialr cases, but there is no specific confirmation either way. This includes the Balmung, the Aldebaran, The Cognitone and the Omnitione (though the books are likely given Summoner's origin in in Allag)
- Sophic Weapons and Weapons of the Sephirot: Like in Bahamut's case it is likely that the Triad's thralls made the weapons, unlike Bahamut's case theirs are even more likely to canonically exist.
- Valerian Gear: My Headcannon is that only one Dungeon per pool that shares gear is where the gear is actually found. Useful considering there is usually only one Unique dungeon per pool. In this case I think that Neverreap is the actual source of the gearsets. Other cases being the Dravanian gear being found in the Antitower and the Valkyrie Gear in Xelphatol
- Demon Gear: Their existence is plausible, but I don't think Allag made them.
- Sycrus Tower Cosplay Gear: mainly because I'm a little skeptical on what use Allag would have for them given the style clashes with the Coil Gear and is a little disimal to the LoTA Gear. The caster/healer headpieces is the main reason I'm questioning their actual existence. However Them being the armor of Meracydians, captured and brainwashed into Allag's forces (Plegthon and Glasya Labolas) or mutated and cloned (Queen Scylla) are far more likely. Especially since the Demiurges wear similar gear.