There seems to be at least 2 sets of items.
1) Brightwood Spear, Walrus Bone Shield, Tiny Coin Purse
2) Everything else.
From killing 500+ "a shambling cube" I've seen many from set 1 and exactly ONE drop from set 2 (Totem of Distraction). I've seen a wyvern that I watched spawn drop a Wyvern Claw (Set 2) and a tiny coin purse at the same time. From what I can tell the lower lvl cubes suck for farming, they vary in level and it's possible depending on level they may or may not drop items from set 2.
Independent from the above example, there seems to be some obviously more rare items like Wurm Lord Shawl, Wyvern Hide Tunic, and the Int/Wisdom earrings, that despite killing 3000-4000 wyverns I can't tell if they are on a separate set of items (such that they do their own roll chance to drop, and could drop at the same time as other items) or that when you roll for an item from set 2 it just has a rarer chance of being selected.
TLDR - Green con "a shambling cube" that spawn prior to maze seem like mostly a waste of time to farm. I've been told by a guildie they got a Wurm lord Shawl from them, I can only assume they killed a high green con or blue con one at 60 and got super lucky, I am not convinced that all green con "A shambling cube" can even drop items like Wurm Lord Shawl, from what I can tell there may be a level requirement for a Skyshrine mob to drop said items, and the "a shambling cube" can spawn low enough lvl to not even have a chance at dropping them.
Link for reference of level variance -
https://everquest.allakhazam.com/db/npc.html?id=5575
Oct Velic who I've seen drop loot from my Set 2 example -https://everquest.allakhazam.com/db/npc.html?id=5577
Maybe it's lvl 43+ so any cubes spawning at lvl 42 can't drop the good loot? Just spit balling and theorycrafting based on my experience there, but my drop rate of something off wyverns/cubes was ~1/16.5 so killing 500+ cubes and seeing 1 item from Set 2 is extremely fishy to me. Whereas the wyverns seem to drop Set 2 items far more frequently than Set 1.