Blood devil

Your powers come from fusing with a blood devil in some way. Unlike others who's magic comes directly from your entity, yours comes from your blood that pours out of your wrist when you so desire. There's probably something on you signifying your demon fusion, such as horns. Using your blood you can not only cast spells but also form it into weapons that allow you to change them mid combat, and once your skilled enough even mid-attack. Your fusion also gives you some smaller demonic powers such as healing. 

Blood Weaponization

When you take this pact at 1st level During Combat you may use a bonus action to use your blood and spawn a melee weapon. Choose what weapon you want to spawn then roll what dice is used for its damage roll, roll that and lose that much hp. You have proficiency with the weapon and use your spell attack modifier instead of what you would normally use. You may use the weapon as a spellcasting focus. You may use this a number of times up to your proficiency bonus. when you reach level 14 you can use this an unlimited amount of times. You may choose to spawn weapons to duel wield, when you do roll the damage dice twice (For example if you were spawning a dagger you would roll 1d4, if you were spawning 2 to duel wield roll 2d4) 

Whenever you cast a spell, or attack with a weapon(including your blood weapon) you may choose to roll an extra 1d6. Take that much damage and add it to your hit or damage roll. you can also choose a1d8 at level 6, 1d10 at level 10 or 1d12 at level 14. you may use this a number of times equal to your constitution modifier + your proficiency bonus

Blood feasting

Once you hit level 6 Whenever you attack someone roll a 1d6, heal that much hp. If your using your blood weapon its a 1d8 instead. the healing goes up to 1d8 at level 10, and 1d12 at level 14 without a blood weapon. 1d10 at level 10, and 1d12+your con modifier at level 14. 

As an action you may roll a 1d4, take that much damage and gain that much AC for 1 minute. This goes up to 1d6 at level 14. you can use this once per long rest. 

Extra attack

Beginning at 6th level, you can attack twice, instead of once, whenever you take the attack action on your turn.

Improved blood weapon

during combat when you use your blood weapon, you may choose to switch it between an attack and extra attack, you may also choose to turn it into a ranged weapon. All blood weapons now deal an extra 1d6 damage. 

Blood assistance

Starting at level 14 you can use your blood to assist others, you may choose a willing target within 20ft of you and choose to heal them for1d4 to 1d10 + your constitution modifier + proficiency bonus. Take as much damage as you heal.

you may also choose to use your reaction to strengthen the attack of someone else within 15ft. Roll 1d6-1d10, take that much damage and they add that much to there damage roll. 

You may choose to use your hit dice outside of a short rest. You may do this twice before taking a short rest

Improved Health

Starting at level 6 you gain 1d10hp instead of 1d8 when you level up. This counts for the level 6 level up as well