If they don't want to change pact of the blade for Wyll...then change Wyll. Astarion has a bite, karlach a internal rage etc..Wyll has passive to add rapier proficiency...just add in the ability to use cha for wpn attacks (just call it a special deal with Mizora).
I liked the idea that was suggested abowe ... basicaly upgrading Pact of Blade into Hexblade by adding this ...
People would still need to take some invocations to make it work properly, but Wyll would work well like Fiend Meele Warlock ... and that is the point, isnt it?
