This is a mod called “Elite Knights Original Weapons” created by “thefirsthunterapprendice”
https://www.nexusmods.com/darksouls3/mods/1142
For more information on how to use the mod, check out the videos made by Sam Chan, who is the translator of the mod:
https://www.youtube.com/channel/UCAYEP2zOevnc65xN90VB5Eg
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