It should be mentioned under General that a ton of weapons from throughout the series return as weapons in XIV. A couple good examples that I can recall off the top of my head from FFXI:

Claustrum, the BLM Relic Weapon, is the staff wielded by Kan-E-Senna.
Tizona, the BLU Mythic Weapon, is one of Raubahn's swords.
Death Penalty and Annihilator are the two guns wielded by Merlwyb. The Death Penalty is both the famous weapon wielded by Vincent in VII and also the COR Mythic Weapon. The Annihilator is the RNG Relic weapon.
The Veil of Wiyu and the Omnilex (the Summoner and Scholar relic weapons, respectively) are from the Tactics series.

And, needless to say, a TON of monster designs were taken directly from XI (Crabs, Colibri, Mandoragora, Raptors, Chigos, Apkallu, Adamantoise, Goobbue, and technically Mammets, since they're just cuter versions of the Automatons that Puppetmasters got) and even some from XII.