Beat all the bosses and got all the tablets (I think) as well as recovered THREE "bonus" items, I've only ever seen people mention two. I have one that increases xp by 1.5, one that increases gold by 1.5, and one that increases tp by 1.5. Forget where I got them.
Also, I managed to steal a pretty awesome weapon called "juggernaut" for ruland, off the tank boss in the sealed cave (290 attack and a special that makes standard attack attack all enemies). I wasn't really consistent in stealing items, were there any cool weapons to steal that I missed out on?
Edit: I did the earth and sky sealed dungeons before I did the sealed caves for the +5 merit ring, is there even anything to use the ring on? Some end boss? Or if I already finished the 2 bonus dungeons and 5 sealed caves is that pretty much it for the game?