Blade Sorcerer

Someone far in the past of your bloodline's history looked upon their sorcerous powers, realizing that their power was merely fleeting. People who wield magic and people who wield blades both suffer different inherent disadvantages, however, your ancestor saw this as folly. They trained to weave their robust magic with potent martial abilities, granting them a distinct edge over foes who fail to question and adapt to their flaws. Thanks to this, your very blood is tinged with the echoes of this power, the power to exert your will through spell and through sword, so that none may best you.

The blade sorcerer weaponized their spells in a way unlike any other. When they cast the spell, it leaves traces or echoes that the sorcerer can then imbue into their weapon. This allows them to channel various effects into each strike, whether it be jolts of lightning, scorching flames, or frigid ice, the blade sorcerer style has evolved to adapt to nearly any situation. Thanks to this, it manages to be both flexible and destructive. It seeks to balance both offense with defense, as they can exploit and even create vulnerabilities on their foes, while also being able to patch up weaknesses in their defenses on the fly. 

Arcane Vigor

When dealing damage with a cantrip, you gain temporary hitpoints equal to 1d6 plus proficiency modifier.
This effect increases by 1 dice level when you reach 5th level (1d8), 11th level (1d10), and 17th level (1d12).

Elemental Resonance

When making a melee weapon attack, you may expend one sorcery point to add 1d8 bonus damage, with the damage type being the same as the last damaging cantrip you cast, as well as add your charisma modifier. 

Proficiencies

You gain proficiency in light and medium armor, as well as the option to choose two melee weapons to be proficient with.

Arcane Blade

Your melee weapon attacks are considered magical for the purpose of overcoming immunity and resistance to nonmagical attacks, and you gain a +1 bonus to attack and damage rolls with melee weapon attacks.

Extra Attack

You can attack twice, instead of once, whenever you take the Attack action on your turn. Moreover, you can cast one of your cantrips in place of one of those attacks.

Adaptive Barrier

You may spend a sorcery point after casting a damaging cantrip to become resistant to the damage type dealt by that cantrip until the start of your next turn. If you receive damage of this type while adaptive barrier is active, you gain 1 sorcery point.

Elemental Burst

When you are hit by a melee attack, for the cost of 1 sorcery point, you can use your reaction to deal damage equal to your sorcerer level, the type of which being the same as the last damaging cantrip you cast, to the attacker, and it must also make a STR saving throw equal to your spell save DC. On failure, the attacker gains a vulnerability to that type of damage until the start of its next turn.

Empowered Resonance

Beginning at 18th level, the damage from your elemental resonance goes from 1d8 to 2d8, and if a creature is vulnerable to the damage of the elemental resonance, attacks applying elemental resonance have their critical hit threshold lowered by 1. This effect can stack with other features that decrease the necessary threshold to critically strike.