Faoimórach

Faoimórach is a sentient blade found in the possession of the Fey creature Bocánach.
This jagged blade cuts flesh upon touch, no matter the force placed upon it. Jagged and imbued with dark energy, this ancient blade of obsidian holds matter that consumes and hungers for blood. The hilt is covered in bristles and thorns and tied with vines.
== Information ==
You gain a +1 bonus to attack and damage rolls made with this magic weapon.
Life Drinker. If the sword is used to kill a creature, you can use your reaction to give yourself 2d4 + 4 temporary hit points. This property can’t be used again until the end of a long rest.
Dark Smite. When you hit a creature with Faoimórach using a melee weapon Attack, you can expend one spell slot to deal necrotic damage to the target, in addition to the weapon’s damage. The extra damage is 2d8 for a 1st-level spell slot, plus 1d8 for each Spell Level higher than 1st, to a maximum of 5d8. The damage increases by 1d8 if the target is an Celestial or a Fey, to a maximum of 6d8. 
Dismemberment. When you roll a 20 with Faoimórach using a melee weapon Attack and the target is below half of its hit points, the sword cleaves through a random limb and severs it from the body.
Sentience. Faoimórach is a sentient neutral evil weapon with an Intelligence of 12, a Wisdom of 14, and a Charisma of 12. It has hearing and darkvision out to a range of 120 feet. 
The weapon communicates by transmitting emotions, sending a tingling sensation through the wielder’s hand when it wants to communicate something it has sensed. It can communicate more explicitly, through visions or dreams, when the wielder is either in a trance or asleep.
== Research ==
Completed by Killian Kir’we
Whilst the blade is jagged and its weight unbalanced, the sword is unnaturally sharp and a simple touch of blade against flesh is enough to draw blood from its victim. It would be deemed a sensible hypothesis that the sword cannot be used to deal non-lethal damage no matter the intentions of the wielder. The urge that the blade has for slaying foes seems uncontrollable.
Holding the blade in hand whilst unattuned sends a surge of unnerving energy through the wielder, their eyes growing sore and heavy as a pain grows in their head the longer they hold it. Before too long, a headache turns into the pain of a migraine, with even the lights of a candle enough to cause discomfort.
Upon the use of the arcane to detect the magics within the blade, glyphs and runes of an archaic giant script appear that is unintelligible even to those who speak and read giant proficiently. It would be assumed that the blade is as old as the script itself and is a relic of ancient times and perhaps crafted in the forges of giant-kin.