Nice Duma! I honestly don't recall what your set used to contain, but this one is certainly heavy on the offense! With a good mix of icon variety! Yeah, there's not much you CAN do for your set without spending a lot of NP. I mean, IF you needed some shields or reflectors for some SPECIFIC element(s) for some SPECIFIC opponent(s) we could talk some weaker shields and reflectors that could at least take a dent out of some of what you were up against. I take it your strategy is using Lens Flare, Warlock's Rage and Sleep Ray to give you up to 3 rounds of Free Attacks, right?
I ask because other than the Downsize! I don't see much in the way of defense. LOL Not that I'm one to talk either with my current set setup. But, I would not be surprised if TNT came up with some way of making us need either MORE than that strategy or something OTHER than that strategy to win some of the battles. I mean, they DID say that there would be some opponents to challenge the veteran battlers. We don't know what that means, but we should expect them to do something about the 3-free rounds strategy. I just HOPE they don't make it so that Shhh! can cancel out Lens Flare and Warlocks Rage by going first. That would really stink! And it'd be even tougher for the newer battlers imho. Though, it would bring things kind of back to where they were with the OLD faerie abilities that only had a chance of freezing opponents, instead of 100% chance of stopping them from acting.
Anyway, if you haven't put much concern into defense, or don't have many defensive items in your SDB, you might consider some items that don't cost an arm and a leg that you could get that might help shave off some icon damage. I don't know the prices, but some items off the top of my head would be some dual duties and defenders like Hanso Charisma Charm to block all dark with a 10 icon attack. Parasol of Unfortunate Demise, to block all Light, and some earth and water icons. Roxtons Trusty Bowie Knife for a 15 icon attack and blocks 75% of Earth. Flaming Oven Gloves may be kinda weak, Blocks 5 Fire and 2 Light, but it's some fire defense, saved my bacon several times when I was a young battler. lol Not sure how they'd work with the max boosts though, still. They're cheap too. Leaf Shield from Illusen's Quests is still good for Earth, Water, and Physical. Just the first few pieces of equipment that came to mind. Altadorian Swordbreaker, only a 6-icon attack, but blocks all Physical. That would just leave Air that's not defended in any of those items, I think. Hmmm..... Double Dryer, the 50% reflector is decent and not too expensive. Let me do some quick looking..... Ok, With your pet's Int-stat, Parchment Cloak would give you protection from several icons, +5 Air icons thanks to your INT being above 150. Or there's one of my old standby items, the Earthen Scorchstone, good for Air AND Darkness. Greater Defense Scroll defends 5 Air Icons too. If you want a Dual-Duty that can defend Air. Bubble Wands, only blocks 3 Air icons, but has a 9-icon attack.
This is all on a budgetary thing of course. There are better options, but like you said, you don't want to get into the millions or tens of millions of NP range. So I'm just having a little fun typing out some of the budgetary items. Anyway, some of these items MIGHT actually help you in a pinch, depending on what TNT decides to throw at us.
I always keep a few items of varied defensive items in my SDB to swap out just in case, old habits die hard after all. Even though, truth-be-told, I've become somewhat complacent with this current battle system and using Lens Flare and Warlocks Rage if/as needed. That's one of the reasons I'm excited for the plot, hoping for a shake-up in the strategies.
Oh yeah, on Heavy Robe of Thievery. Provided TNT gets Stealing fixed in the BD, I think you'll enjoy it. Especially if you steal a really good weapon from your opponent! Mine has been sitting in my SDB since stealing broke, gathering dust. I'm looking forward to being able to using it again, fingers crossed!