The Noble Unlocker's Ascendancy

Born into a noble family of master swordsmen, fifteen-year-old Hiraku Mato was destined to inherit the legendary Sword Saint skill at his coming-of-age appraisal ceremony. But when the ceremony reveals his gift to be the seemingly worthless "Unlocker" skill, his future crumbles before his eyes. With no historical record mentioning his skill, people assume it can only do mundane things like open doors and windows. But a chance encounter uncovers its hidden potential: the ability to unlock status windows, hidden skills, and even rare drop items. Armed with this cheat-like power, Hiraku sets out to carve his own path in this action-packed fantasy!

(Source: Manga UP!)