I saw a guide a while back, and it included "Basic shit to not do: give +stress items to people with stress quirks" I assume this is only for units with negative quirks that give extra stress, but I want to make sure there is no crazy interaction caused by giving a unit with -10% stress damage an Ancestor's item for example

Speaking of trinkets and stress, how good are +stress trinkets? Items like the heads, Ancestor items, or Legendary Bracer look quite nice, but it feels necessary to have a +Acc trinket like Sun Ring or Focus Ring, so it's hard to run a -stress trinket to balance it out. Especially with Sun Ring, that's already extra stress so having a second stress trinket seems so not worth the extra damage.

For party comps, Jester+Vestal feel almost mandatory. I've had some success with HM for stress healing at higher levels and off healers like Arbalest or Crusader for healing, but in the long run Jester and Vestal just do so much better.