When you are subjected to an effect that allows you to make a saving throw to take only half damage from a spell, you instead take no damage if you succeed on the saving throw, and only half damage if you fail. This can be done once per short rest.
Does not require attunement. Uses normal dagger stats.
Though mithsteel is known to be too brittle for use in weaponry rather than armor, its properties could still be used by those unfit to don such heavy material, but with the finesse to wield.