Final Fantasy XIV update 5.45 relic weapons are locked behind the completion of "The Lady of Blades" on the South Front of Bozjan.
Before you can return to the Memories for Gerolt culture for shiny new relic weapons, you'll need to complete one of Final Fantasy XIV's most boring “raids”. Relic weapons are locked behind the “Save the Queen” quest chain, so if you've slept on your Bozjan Southern Front rank, you'll need to spend time grinding up Skirmishes (FATES) and Critical Engagements (Super FATES which are boss fights) in in order to earn enough Mettle (Bozjan Rank Experience) to reach Rank 10. Complete all of the story quests that appear whenever you rank in the South Bozjan Front, and eventually you will pick up " The Lady of Blades ”and unlock Castrum Lacus Litore.
Castrum Lacus Litore is, to be polite, a pain in the ass to be erased. Not necessarily because it's difficult: the "raid" only appears as a critical engagement when there are enough rank 10 characters in an instance of the South Front of Bozjan, and it only reopens one. hour after spawning. You not only need to be active at the right time, but you also need to hope that there will be enough people around the queue for this, as you need at least 18 players to successfully clear the instance. . You won't win Mettle in Casrum Lacus Litore, but you will definitely lose him. You might want to consider creating or joining a Party Finder group for this one, and watch a few videos to make sure you're able to clear the Castrum and complete "Lady of the Blades".
Once you have completed "The Lady with Blades" you can take the first quest in the Final Fantasy XIV Patch 5.45 "Saving the Queen" story arc, "A Sign of What's to Come". Complete this and the next quest, “Fit for a Queen,” to unlock the next stage of the Blades of Gunnhildr relic weapon quest. Speak to Gerolt to grab "In the Image of the Queen" and you will be tasked with cultivating memories again after starting the next quest "Switch Weapons".
You'll need to cultivate Relic Weapon Memories again, and they can be found in Alliance Raids this time around.
The first stage of Update 5.45's Blades of Gunnhildr Relic Weapon Chain will require 15 Loathsome Memories of the Dying, and these can be earned either randomly (with a low drop rate) from Critical Engagements to Bozja, either by completing one of the crystal towers. Alliance raids from A Realm Reborn (you will earn a souvenir per achievement)
Then you will move on to the quest "The Resistance Remembers" and you will have to cultivate 18 haunted memories of the dying. These are absolutely unrelated to Bozja, but there are still two ways to earn them. You can either grind the FACTS of Gyr Abania or complete the Mhach raids from Heavensward (as in the previous step, you will only gain one memory per raid end). Oh, but there is another set of memories to cultivate for this quest: 18 Vexing Memories of the Dying. These are earned by raising Othard FACTS, or by completing Stormblood's Ivalice raids (second verse; same as first).
Once you've acquired all of these memories and wiped the blood from your eyes, you'll move on to the final quest in the Blades of Gunnhildr Relic Weapons quest chain from Final Fantasy Patch 5.45: "A New Path of Resistance." This one doesn't require memories, but 15 time-worn artifacts. Here's the kicker: you have to either farm them from the new "raid" Delubrum Reginae added to Bozja in patch 5.45 (think Castrum Lacus Litore, but new), or from the Palace of the Dead. Luckily, Delubrum Reginae is unlocked alongside the new Relic Weapons of Blades of Gunnhildr quest chain when you complete "Fit for a Queen", and you can match up by speaking with Mikoto in Lost Tracks, or Sjeros in Gangos, forming so a party will be easier.
This last step is the one that allows you to choose the stats of your Relic Weapon. Don't worry about making the wrong choice: In Final Fantasy XIV update 5.45, these relic weapons can be modified with an Ethereal Sealant, and it only costs 100 poetics (so, quality change). Now with all that said, I recommend completing the rest of the 'Save the Queen' Update 5.45 quests, as I'm sure the next Relic Weapon quest chain will be locked behind you. Don't get caught with your pants around your ankles like some of us (including me): clear this quest chain now to save yourself a bit of heartache later.