Proposed Changes
Bewitching Tongue
Prerequisite: friends cantrip
You gain proficency in the Persusasion skill.
The duration of your friends cantrip increases to 1 hour or until you cast it again. Additionally, you can change the creature you choose that isn't hostile towards you as an action on your turn.
When you cast this spell again or when it ends, all creatures affected by this spell must succeed on a Charisma saving throw against your spell save DC or be unaware they were charmed by you.
Breath of Zehir
Prerequisite: poison spray cantrip
A creature that is damaged by your poison spray cantrip is poisoned for 1 minute. An affected creature makes a Constitution saving throw against your spell save DC at the end of each of its turns, ending this effect early on a succcessful save.
A creature becomes immune to poison condition caused by this invocation for 24 hours whenever the poison effect ends.
Eldritch Aegis
Prerequisites: blade ward cantrip
When you cast blade ward, choose a damage type. You have resistance to the chosen damage type until you cast this spell again or until you take damage of the chosen type.
Lightning Lash
Prerequisites: lightning lure cantrip
A creature damaged by your lightning lure cantrip can't take reactions and can not willingly move away from you until the start of your next turn.
Raven Queen's Claw
Cut.
Singing Blade -> Deafening Blade
Prerequisite: booming blade cantrip
A creature sheathed in booming energy is deafened and can't take reactions until the start of your next turn.
Still might still be too dull.
Sisphyean Stones -> Warding Pebbles
Prerequisite: magic stone cantrip
When a creature is hit by a pebble created by your magic stone cantrip, the pebble maintains its magic until the start of your next turn and begins orbiting the hit creature.
The next time that creature makes an attack roll against the creature that threw the pebble, as a reaction you can cause the pebble to strike the affected creature dealing an additional 1d6+ your spellcasting modifier bludgeoning damage and impose disadvantage on the attack roll. The pebble then loses its magic.
Other Notes
It might be worth adding Potent Cantrips (Cha on hit) to any of the cantrips that don't already get it within their invocation if their invocation doesn't already boost damage. Poison spray getting Cha on hit would make it x10 stronger