Is there any way for us to disable equipment slots so that when we do not equip an item in a particular slot, we are not provided with a "fallback" set of cards? The reason I ask is that I'm at level 8 with my main party and I've noticed that, with the increased deck size, individual pieces of gear no longer make a significant contribution to battle performance. Worse still, I've seen my warrior sit out round after round because he draws zero attack cards. I recently ran through a level 6 dungeon with a level 1 team and did better (zero deaths) than a run with a level 8 team (2 deaths). This should not be happening. Instead of getting better over time, the team is getting worse. I'm spending more time waiting for a good card to come up now that I'm at a higher level. This seems counter-intuitive. Rather than gaining ever more equipment slots, I'd rather have the ability to disable them, to trim down the deck size. Right now, not equipping an item in a slot means we're provided with "fallback" cards, e.g. an empty divine item slot gives you 3 Wavering Faith cards. There was a thread with similar feedback (I can't link to it; it's titled [Feedback] Luck and Progression), but this particular suggestion wasn't made.
There's definitely a rough spot between lvl 4 and lvl 10, where your card collection isn't expanding quickly enough to handle the new equipment slots you're unlocking. My advice for expanding your collection more quickly is: 1) Play a couple of multiplayer games in addition to the campaign. You get much better gear for the first win than you'll find in almost any campaign. 2) Buying a few choice items from the stores can make a huge difference. I found myself selling most of my inventory between runs in order to grab the one or two items which would fill those new slots. Yes, it sucks to ditch all your hard-earned loot, but you'll get much better loot later on.
There have been plenty of threads with this same suggestion, and from a game design standpoint it shouldn't be done. Here: If you could disable anything at will, then you'd just disable down to an absolute minimum of devastating cards. Like the single Legendary item you earned that one time, plus a default Move card. Because you've unlocked those slots, you are now beyond "easy mode" and have to use the full deck size. Yes, it's hard, but this is the deck size for which the entire game is designed, all the way from here up to the hypothetical level 50. As neoncat says, it's only going to get better as you play more. Enjoy the ride as well as you can! And if you're curious, I posted elaboration in that other thread, too.
