The way I'd do it is with cantrips
"Gishblade"
Evocation cantrip
Casting Time: 1 action
Range: Self (5-foot radius)
Components: S, M (a melee weapon that deals slashing damage)
Duration: 1 round
You brandish the weapon used in the spell’s casting and make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack’s normal effects plus an additional 1d4 fire damage. The weapon is also magical.
then you'd take "gishvocations" to boost the cantrip.
Arcane Channeling: You can cast flaming hands or thunderwave as a bonus action if you cast gishblade.
Aegis of Ensnaring: A target hit by gishblade is restrained.
Brightblade: You learn the light cantrip. When you cast gishblade, the additional damage deal is radiant.
Deathknight: When you cast gishblade, the weapon's damage becomes necrotic and on a hit, the target cannot heal until the start of your next turn.
Elfblade: When you cast gishblade, you may use Dexterity instead of Strength for the attack and damage rolls of melee attacks
Roaring flame.: You deal additional damage with gishblade equal to your Intelligence modifier
Spellstab: You can cast gishblade with melee weapons that dead piercing damage.