Guess I'm here for a little while longer.
If "missing" (not dealing any damage) isn't an option, you're just assigning different amounts of damage...and that's what the damage roll does. This seems pretty straightforward to me, but it's well-established that I'm a weirdo. I also don't know why fireball keeps coming up when I'm describing magic missile.
I would love to see a Lunge mastery, something that extends your reach with the weapon (especially the spear and quarterstaff). That would be amazing for skirmishers. We've tried to house-rule that in the past with the Bonus Action, but 5E's action economy makes it too expensive for monks and fighters.
I'd also like to see a Block or Deflect mastery for greataxes, using the broad blade of a greataxe as a rudimentary shield to boost your AC for a short time. Without seeing how Mastery is deployed in the game, though, this could cause problems.
"More damage" is probably the least creative way to improve weapons, IMO.