bump

As a rule:

If you can equip it, it's permanent.  Equippable items appears in a specific row.

If you can use it out of combat, it's a permanent bonus, but the reverse is not true, i.e. just because something can be used in combat, does not mean that it is not permanent.

If you cannot use it out of combat, chances are, it's temporary.

One big exception, which in my book is a bug: if a summoning item can be used out of combat, but is used in combat, the summon may go away after the combat is over. That may or not may be still true, because since I learned it could happen, I stopped risking it.

The in-game hiergamenon is useful (not searchable, but things are listed alphabetically). Look under equipment

Yes it can be quite confusing.

Just found a rainbow potion (forget name) which tells me it makes the user impervious from normal damage for 3 turns.  I'm guessing that means combat rounds and not game turns (i.e. seasons) but who knows?

The general thing I figured goes if I can use it on the strategic map then it's made for the strategic map. If I can't it's a tatical map thing. There are exceptions for this rule, but generally that's a good way to start.