Madscientist

Yes, all passive abilities stack, all active abilities do not stack.
Spells, potions, auras, stances and weapon modals count as active, so they do not stack.
Rule of thumb: Things on the right side of the talent screen stack, everything else does not. ( there may be exceptions)
 
The basic rule ( passives stack, actives not ) is nice and simple.
But the game does a bad job telling us what counts as active and what as passive.
 
suggestion:
For everything that changes stats ( attributes, acc, defenses, power level, AR, penetration, maybe others ) add a tag if it counts as active or passive.
If you give us the rule "passives stack, actives not" everyone can see what can work together and what gets suppressed then.

Berserkers get confused when they use frenzy.
Confused means that all abilities (damage, healing, status effects) hit all allies and enemies in the area.
That means healing abilities will heal enemies and allies and damage abilities ( carnage!) will damage allies and enemies too.
 
In order to avoid the confusion you should have resistance to intelligence afflictions, use an intelligence inspiration on the confused char ( it will remove confusion but you do not get a buff ) or use an ability that removes or suppresses status effects.
Paladins can learn a talent that gives them resistance to intelligence afflictions.When you learn it you will not get confused when using frenzy.

Somehow the problem solved itself.
 
When the bug happened, loading another save did not change anything.
It looks like closing the game completely, shutting down the computer and continue on another day solved it.
Now all tolltips are shown for all items, including soulbound ones.