I agree that something needs to be done with crafting tools and ingridients. Maybe tag tools as ingridients as well? That way everything can be one tab. But it's not a very good solution for weapons like knives, axes etc. which are used both in combat and as a crafting tool.
The other, more elegant option, but one that requires much work is to ditch manual combining of items and go with items list:
-There should be a separate window, which contains all the items you can create. It can be a reworked Recipes tab.
-This window fills up as you collect recipes.
-The items that have enough ingridients to create them and sufficient crafting level are colored green, for example.
-The items that don't have enough ingridiens and sufficient crafting level are marked red.
-Beside each item should be shown required crafting level, amount and type of ingridients needed to create an item.
This system has been done in many games and is quite convenient - you don't have to rummage through inventory at all and can easily see what you can craft. Crafting itself is done with just one click of a button.
In short, I'm talking about a crafting system similar to TES: Skyrim: