Now I know there are going to be a lot of people against this idea, but it would add a LOT more build versatility in the game for all of the classes, and maybe even open up some new end game builds.
My idea is that regardless of your weapon type, Heavy Attacks should return your highest resource. Say I'm doing a Magicka Nightblade, and I'm an up in your face build with a two handed weapon, or dual wielding maces, that my heavy attacks should restore mana instead of Stamina, and that my Magicka should factor into my basic attack damage instead of my Stamina and vice versa for staves.
Admittedly I have no lore defining reason why this should work, but truth is, I just want some more freedom of creativity in my character building, and still be viable in PvE/PvP.