According to TibiaWiki information:
Amazon Helmet: Dropped by Orc Warlord during raids on Femor Hills (unannounced) and Thais.
Amazon Armor: Dropped by Orc Warlord during raids on Femor Hills (unannounced) and Thais.
Amazon Shield: Dropped by Orc Warlord during raids on Femor Hills (unannounced).
Source: https://tibia.fandom.com/wiki/Amazon_Armor#History
Daily checks on Femor Hills are extremely recommended due to the rarity of the mentioned drops.