Yes thats very odd indeed.. Perhaps you are correct in that you are experienceing a bug.. Certainly by lvl 17 you should see change.. While some of the items, for me, may be the same, some are not as well.. In this playthorugh, im still at the point where Novice, and Adept lvl spells are the majority.. I havent yet seen a master spell.. My highest Skill for any of my chasracters is rank 3..So if the vendor is only changing a few stock items per lvl up/24hr/etc. then its a higher chance that there will be similar items.

Like yupper said, this isnt like Diablo where your supposed to advance all gear every lvl or 2.. At lvl 20 you may still have the same belt you initially aquired.. You may find a better one.. Bu since the stats are +1, or sometimes +2, they dont really get underpowered.. The same cannot be said for weapons, as those you want changed regularly.. But gear pcs seem to hold value, even later on.. Ones with Armor stats, or % based stats advance a bit better however.. Even though i have lot of purple and gold items, some of them have only one stat on them, since they were found early. (i could have sworn Larian stated we would NOT find good gear early often, but later on, blues would be common place)

As for Tenebrium, i thought the game was possible to complete even avoiding it completely, but i could be wrong.. I tihnk i Gave madora a Tenebrium 2 handed mace, and Bairdotr comes with a point in Tenebrium, but thast all i ever did.

As for Dialog, we'll have to agree to disagree.. I dont know, or care about the trait the dialog gives.. I play it as i setup my character, an anything that comes of a dialog choice, is a bonus..Some of the traits i have work, some make no sense.. Like Backstab on my Fighter, or Crafting on my mage who doesnt craft.....For the most part, the stats are atleast useful to everyone.. Like Leadership, or Crit Chance, or Immunity to fear and charm.. These are helpful to everyone..Even if not Optimal.. There are only a very small few that you wouldnt want.. Immunity to fear actually saves you a point in Talents.. I think you only get 6 talents, so freeing one of those up is godly..