Hunter's Ring
The Hunter's Ring raises your Dexterity by five points, enough for you to one-hand various weapons including the Irithyll Straight Sword. The ring is found at the Grand Archives, accessible after defeating the Abyss Watchers, Yhorm, Aldrich, and Dragonslayer Armour.
Dragonslayer Armour
SL1 Dragonslayer Armour, Dark Souls III
This boss is weak against magic and fire. Buff the Raw Broadsword+10 with either Pale Pine Resin or Charcoal Pine Resin. Phase one of the fight can be rather difficult because you have to constantly dodge the boss' attacks. Stamina management is crucial during the whole fight. Equip the Chloranthy Ring and the Grass Crest Shield to boost your stamina regeneration. You might also want to equip the Carthus Bloodring to boost your roll i-frames. Stay close to the boss and bait the delayed one-handed overhead attack and the charged two-handed overhead slam. These attacks give you plenty of time to strafe behind the boss and deal R1 x 2. In fact, the safest windows to attack are during the boss' delayed and charged overhead attacks. The boss has the same move set in phase two, but the difficulty is compounded by the aerial support from the Pilgrim Butterflies. Occasionally, the Pilgrim Butterflies would shoot fireballs at you and fire a charged laser beam. Move from one end of the arena to the other end as a means of avoiding the fireballs and laser beams, all the while baiting the above attacks from the boss. Pay attention to the audio cue from the Pilgrim Butterflies to help you gauge when to run away to dodge the butterflies' attacks. The most devastating projectile from the Pilgrim Butterflies is a giant energy ball that explodes on impact, which would most likely one-shot you. Look for the audio and/or visual cue to help you determine when the giant energy ball is incoming. Use the fountain structure at the middle of the arena to block the projectile.
Defeat the Dragonslayer Armour and light the Grand Archives bonfire.
Grand Archives
SL1 How to get Crystal Scroll, Dark Souls III
Farming Titanite Chunks at Grand Archives, Dark Souls III
Open the gates of the Grand Archives and enter the building to find Crystal Sage spawning. This is now a mini-boss. Throw Dung Pies at the Sage until he is inflicted with toxic, then cast Poison Mist to poison the boss. Leaving the Crystal Sage alone and he would constantly harass you as you move through the area. Kill the Crystal Sage to receive the Crystal Scroll. Give the scroll to Orbeck to advance his quest line. Purchase all sorceries from Orbeck, exhaust his dialogue to receive the Young Dragon Ring and the Slumbering Dragoncrest Ring. The Slumbering Dragoncrest Ring will be useful for cheesing two mini-bosses. Exhaust Orbeck's dialogue again, warp back to Firelink Shrine, and Orbeck should have left the shrine. His summon sign is available near the arena of the Twin Princes. If you have been following Sirris' quest line, her summon sign should be in front of the arena of the Twin Princes. Summon Orbeck and Sirris to help you clear the area and farm Titanite Chunks.
Location of Avelyn, Dark Souls III
Titanite Chunk x 11 at Grand Archives, Dark Souls III
Location of Greirat's Ashes, Dark Souls III
Undead Bone Shard & Estus Shard at Grand Archives, Dark Souls III
Location of Scholar Ring, Dark Souls III
Location of Hunter's Ring, Dark Souls III
Grab the Avelyn. This crossbow shoots three bolts at a time, immensely useful for dealing chip damage to most enemies. You cannot one-hand the Avelyn, but it can be two-handed while equipping the Knight's and Hunter's Rings. Titanite Chunk x 11 are found on corpses scattered throughout the area. Find Greirat's Ashes. Give the ashes to the Shrine Handmaid and she would sell all of Greirat's wares, including Splintering Bolts and Exploding Bolts. The Scholar Ring is hidden between two book cases. You must pull a lever to remove the book cases. The ring raises your Intelligence by five points, enough to allow you to cast the weapon art of the Storyteller's Staff. The staff will be used to poison various bosses and mini-bosses. The Hunter's Ring is found underneath the rooftop where the Gertrude Knight x 3 spawn. This ring, together with the Knight's Ring, allow you to one-hand the Irithyll Straight Sword and two-hand the Dragonslayer's Axe. Grab an Undead Bone Shard and an Estus Shard. Your Estus Flask should now be at +10 and you now have 15 uses of the Estus Flask.
Titanite Slab x 3 at Grand Archives, Dark Souls III
Titanite Slab x 3 can be collected at the Grand Archives. One is hidden behind a book case. Pull a lever to remove the book case, thus revealing a treasure chest. The second slab is automatically deposited into your inventory after defeating the Gertrude Knight x 3. The third slab is found below the second elevator at Lothric Castle. The first elevator at Lothric Castle is a shortcut to the arena of Dragonslayer Armour. The second elevator cannot be activated while you are at Lothric Castle. You must make your way to the entrance of the arena of the Twin Princes and look for an alcove to find an elevator that takes you to Lothric Castle. This is the same elevator puzzle as the one at the Undead Settlement.