OK, I may have a novelty idea
How about indirect control mechanisms?
As an example, take a look at this game called Gish.
It has 4 control functions: sticky, glide, heavy (also expands) and move. But by combining these simple controls, you can do more. Sticky can help you move across a ceiling, but you can also stick objects to yourself, by combining it with the move and heavy function, you can throw objects, and with some skill, control very precisely with what force and under what angle the object is thrown.
A direct "throw" function wouldn't be able to have such level of control, at least not without a very complex control scheme, with separate controls for the angle and force.
Just play the demo to see what I mean, or watch a YouTube playthrough video about the game instead.
Maybe in your new game, you can give the character the functions:
walk-movement, charge, jump, swing, hold, let go.
The swing control can swing a sword, but also throw objects (including that sword, regardless of whether that is a wise thing to do with your sword)
The swing animation takes a certain amount of time, by pressing the "let go" function at the right time, the player can control the force an object is throw. Combine it with walk, and the object is throw with even more force, combine it with a short charge, and even more.
Hold, move and let go, without swinging will just move object. (that don't fit into your backpack) Even heavier objects can be dragged or pushed this way.
Walk into a door, and it will just open, unless it is locked, charge into a door, and you can attempt to break it. Drink a speed elixir, then charge, and you break with more force (useful for higher quality doors) A player can decide to either look for the key somewhere in the dungeon, or beak in, and sometimes even using up a speed elixir to do so.
Combine jump with swing, and your character will hit the enemy with more force in one blow. Combine charge, jump, and swing, and, well, you get the idea. The amount of time you hold charge, and jump determine the exact force of the blow.
Combine it with an environment where many objects are lose (destroyable)... Charge into a lose staple, and the staple will tumble, maybe even into an enemy.
Using indirect controls, the player gains a great amount of freedom, and very precise controls with a simple control scheme.
It also puts playing skill into the equation, instead of just helping the player with the most uber items.
Indirect control isn't a new invention (after all, Gish has it) but I know no Action RPG game that uses it, so it would certainly set the game apart from the already existing ones. And gives people more reason to play it instead of just playing DiabloII.