The strongest black knight has changed jobs to a battle maid is a Manga/Manhwa/Manhua in english language, Action series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.nl fastest updating comic site. The Summary is

Albright, who was famous as “the strongest Black Knight”, was reincarnated as a girl, Maria, whose ribbon suited her well for same reason. Maria, 16 years old, is currently a maid in the Marquess of Urband family in attendance to the Daughter of the Marquees, Relena. After Relena became engaged to the 4th Prince, the area around Maria had gotten busier…