If you make items only have a single application then you can get rid of any verb-object disparity. Instead you'll have a wands button, a potions button, a food button, etc. Not my sort of thing personally, mind - means 3 clicks for any action (wands button, choose wand, choose target).
You could also have an interface a bit like Dredmor's, with selecting an item skill to make that your active skill, so whenever you click on the map it applies that item or skill. Items that are just used directly (food, potions) can just be clicked on within the inventory, or held on to drop.
Hmm, another version of the first suggestion - you have a wands button, a potions button, a food button etc. For each one you have a "default", which will be your first picked up item of that type. Clicking the button activates that item. Holding the button lets you choose a different "default". As items get used up the default will cycle to the next in the list. Icons would show you what is the current default.