Darkvision lets the creature perceive darkness as dim light. It doesn't change the lighting to dim light. Similarly darkvision allows a creature to perceive dim light as bright light. It doesn't change the external condition to bright light

Your Strength score increases by 2, and your wisdom score increases by 1.

Demonic Claws. Your claws are natural melee weapons. If you hit with them, you deal slashing damage equal to your Strength modifier and an additional 1d4 necrotic damage,
instead of the damage normal for an unarmed strike.

Whenever you are within 5 feet of a small or larger non-conjured non-construct non-undead
creature that you killed that turn, you may use a bonus action to gain a level of Bloodlust. As shown in the table below, you gain an effect for each level of Bloodlust for as long as you have it. At the end of each of your turns, if you have not gained a level of Bloodlust on that turn, you lose a level of Bloodlust.
Whenever you reach 6 levels of Bloodlust, you can no longer gain levels of Bloodlust until you finish a Long Rest, but you also do not lose levels of Bloodlust for the next 6 hours.