I always saw tool slot as more of a "convenience" thing - you're in a fight, you can put spense there, you're doing some mining, you put a pickaxe there, you're herbing up, you put moss there, etc. Now, torches are a bit different, because the other things I mentioned can be 'U'sed from inventory, and torches cannot. And, of course, once you get your first orb, it's no longer a tool slot. It's an Orb slot ;) for whichever +10 you prefer.