Corrupted blade

You touch a nonmagical weapon. Until the spell ends, enemies hit by that weapon must make a constitution saving throw. If they fail, they must take 1-D4 Necrotic damage for 3 turns or until they pass their saving throw.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the afflicted also suffers -1 to AC and all saving throws for the duration of the spell. When you use a spell slot of 6th level or higher, the damage increases to 1-D6.