I was specifically trying to a void crit fishing class. That's pretty much what the Champion is. I also don't like the once a day turn a miss into a hit or a hit into a crit stuff.
What about possible just making the damage die to all weapons one size larger for a Slayer instead of adding together ability scores. A maul an greatsword would become 2d8 or 3d4.
Or just give a scaling 1(w) bonus to each hit with a melee weapon. It could start as a 1d4 at low levels and move up one die size every 4 or 5 levels.
Any of these things benefit the TWF more, but I'm ok with that because it feel like it needs to be a little better anyway.