There is a huge range in power outcomes of rewards for quests / spoils, which is for the most part interesting, but there are a couple of things that appear to be gamechangers and really unbalance the scenario.
The quest which give Panca archers is quite easy to handle very early on, and once you have them you can pretty much steamroll everything in the early game.
I'm not at the game right now so can't remember the name of the sword, but the one that gives you mana blast becomes the mid to late game changer. Once you have built up a good mana stockpile this becomes a one hit kill on pretty much anything even when resisted, and doesn't require a powerful caster to do it. Last night I used it to finish the Arena. Pretty much nothing else I had could toch the obsidian golems at the end, so I just had meat shields hold them off long enough to mana blast them one by one. Always resisted, always lethal
I'm sure there are others, but these are the ones I have found, with the archers in particular giving ludicrous momentum early.