- "Have you been to the giant castle north of here? That's Hyrule Castle. It's said to fallen to ruin over one hundred years ago. I used to sneak in there to salvage ancient treasures, but its too dangerous to go in there now. These days its surrounded by an eerie mist and savage machine-like creatures. Back when it was safer, I went in looking for this ultra-rare equipment that once belonged to the royal guard. It's legendary among collectors, but I was never able to find any._."
- — Parcy
Parcy is a character from The Legend of Zelda: Breath of the Wild. She is a Hylian who can be found in a region of Hyrule in the Riverside Stable. She is a scavenger and treasure hunter who used to sneak into Hyrule Castle until the seal Princess Zelda placed on Calamity Ganon began to weaken which caused Hyrule Castle to become too dangerous for ordinary people like herself to even approach due to the corrupted Guardians that patrolled in and around Hyrule Castle.
She reveals to Link that she used to search for ultra-rare equipment once used by the Royal Guard though she never found any and it has become too dangerous for her to continue venturing into Hyrule Castle. Unbeknownst to her, Link just happens to be the Captain of Princess Zelda's Royal Guard who is on a quest to defeat Calamity Ganon and the only person capable of accessing the Hyrule Castle. This results in the Side Quest "The Royal Guard's Gear" in which Link must retrieve a piece of equipment from the "Royal Guard" series which are weapons, shieds, and bows originally created by the Sheikah to combat Calamity Ganon but their low durability made them impractical despite their high attack power however due to its rarity the equipment has become legendary among collectors making it a valuable find for scavengers and treasure hunters like Parcy. Her revelation that it was once safe to enter Hyrule Castle indicates that Princess Zelda was able to keep Ganon under seal in the one hundred years since the Great Calamity and it was only recently with Ganon growing stronger and area around the Castle became more dangerous in response to Link's awakening from the Slumber of Restoration.
Link can find this equipment while exploring Hyrule Castle with some of it being wielded by enemies found in the castle. Activating the Saas Ko'sah Shrine at the Docks can make Link ventures to the castle easier as it allows him to warp back to the castle if he must leave should it become too dangerous to continue. Once he has acquired some Royal Guard equipment he can return to Riverside Stable to show it to Parcy who will give him a Gold Rupee worth 300 Rupees. After completing it, she will trade either a Topaz, Ruby, or Sapphire for any piece of the "Royal Guard" series whether or not it is damaged. Trading the Royal Guard equipment for gemstones is useful as the equipment's poor durability means to doesn't last long before breaking and the gemstones Link receives from her can be sold for Rupees. The weapons will respawn inside Hyrule Castle every Blood Moon. The Royal Guard series consists of the Royal Guard's Bow, Claymore, Shield, Spear, and Sword.
Though technically part of the "Royal Guard" series and even more valuable, the Royal Guard Cap, Uniform, and Boots obtained during "The Champions' Ballad" DLC Side Quest "EX Royal Guard Rumors" cannot be traded nor will Parcy even recognize it as being associated with the Royal Guard, though her knowledge of history seems to be lacking in certain areas as she is unaware of what Guardians are given she calls them "machine-like creatures" nor does it seem she is aware of the fact Calamity Ganon is sealed within the castle.