One of the hardest achievements ever (so mush grind) to get this you need to get all rare weapons
look at your inventory for what weapons u don't have and google it
Tail Weapons:
Drake Sword
Dragon Greatsword
Dragon King Greataxe
Moonlight Greatsword
Priscilla's Dagger
Rare Weapons:
Black iron Greatshield
Astora Straight Sword
Black Knight Greataxe
Black Knight Greatsword
Black Knight Halberd
Black Knight Shield
Black Knight Sword
Blood Shield
Channeler's Trident
Crest Shield
Crescent Axe
Dark Hand
Dragon Crest Shield
Dragon Tooth
Dragonslayer Greatbow
Effigy Shield
Giant's Halberd
Grant (find this before killing Neto)
Gravelord Servant (find this before killing Neto)
Havel's Greatshield
Sanctus (find this before killing Neto)
Silver Knight Shield
Silver Knight Spear
Silver Knight Straight Sword
Stone Greatshield
Stone Greatsword
Velka's Rapier
Boss Weapons:
+10 Hammer + Smough's Soul = Smough's Hammer
+10 Spear / Rapier + Ornstein's Soul = Dragonslayer Spear
+10 Scythe / Halberd + Priscilla's Soul = Lifehunt Scythe
+10 Dagger / Sword + Gwyn's Soul = Great Lord Greatsword
+10 Shield + Moonlight Butterfly's Soul = Crystal Ring Shield
+10 Rapier / Spear + Moonlight Butterfly's Soul = Horn of the Moonlight Butterfly
+10 Katana + Quelaag's Soul = Chaos Blade
+10 Scimitar + Quelaag's Soul = Quelaag's Furysword
+10 Fist Weapon + Iron Golem's Soul = Dragon Bone Fist
+10 Axe + Iron Golem's Soul = Golem Axe
+10 Bow + Gwyndolin's Soul = Darkmoon Bow
Catalyst + Gwyndolin's Soul = Tin Darkmoon Catalyst
+10 Shield + Sif's Soul = Greatshield of Artorias
+10 Dagger + Sif's Soul = Cursed Greatsword of Artorias
+10 Broken Sword + Sif's Soul = Greatsword of Artorias
have all these weapons and u got it