merchant give you only Sx (~50K IIRC), aram heirlooms a lot of potions (and three maranite cloack) and slime only slime consumables. so this three is the obvious to drop if you need sacrifice something. for the reserve in your situation I will go for ardoheim bandit, i think.
for a guide, the only two somewath keep up to date to my knowledge are
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.
for my playthorugh keep in mind anything after the big event in the end of chapter 4 nothing is set in stone, investment mostly, and i think will revision it onlky after the next chunk of content will be released in full (i don't think will be a double release like the ardofrd summit or the 3AW, but it can be the case). the fact is the early section of chapter 5 are basicaly investement free (none of the outcome are tied to some investment done after that event), so barring the investment choices you can play straight to the end of the content (the only little change to do is make demonic undestanding research before deep delving for be able to craft the final custom weapon for aka).