Seikenshi-sama no Maken-chan

Synopsis

Kale is a newly promoted paladin sworn to protect the kingdom, but during the ritual of choosing his own holy sword, he awakens a "demon sword" that can take human form! The Demon Sword is considered a dangerous entity because of its overwhelming power. However, when the demon sword's human form is a beautiful girl named Reece, who looked at Kale with adoring eyes calling him master, Kale couldn't help but think... "She's cute...very cute!!!!" Thus Kale decides to do everything possible to keep Reece happy and keep her power under control, but...!? (Source: Pixiv, translated)