Acheron Dagger

Description: This hunting dagger was once in the possession of a Ramul Hollywrought before he was cut down in the Gloaming. It's handle is formed out of a kind of dark blue marble that's cool to the touch, with a statue of a fair woman forming part of the grip underneath the front of the blade.
The blade itself has been made with dull iron, but on close inspection you can see cracks that reveal the shimmering of gold magical energy. If you press it against your ear, you'll cut yourself, but you'll also hear a faint but pleasant humming.
Statistics: The Acheron Blade requires attunement in order to gain any of the following effects:
You gain a +1 bonus to attack and damage rolls made with this magic weapon. Whilst this dagger is on your person you gain advantage on all throws made against being charmed (or immunity if you already have this).
Unseelie Blessing: While holding the dagger, you can use an action to give yourself 1d4+4 Temporary Hit Points. This property cannot be used again until the next dusk.
Dischordant Strike: When you hit a creature with an attack using the Acheron Dagger, you can fill the target with an unsettling dread: the target has disadvantage on the next Saving Throw it makes before the end of your next turn.
The creature ignores this effect if it's immune to the Frightened condition. Once you use this property, you can't do so again until the next dusk.