The toolbar slots are limited because of the off-hand toolbar. I like to have all my tools on my toolbar :) Let us have the whole toolbar and introduce right click or shift click to equip something in your off-hand.
You could allow food and potions to also be able to be selected with the main hand as well then maybe? If i have a shield on my off-hand, i could have a grenade in my left, it opens up other avenues of weapon combos.
Also you should be able to unequip an item and sheath your weapon by just re-pressing the button for that weapon/item. pressing H sheaths both hands and is clunky.