First I'll thank Gigantus for having me look at this phenomenon more closely since I'd thought of investigating it but for various reasons it was put aside to do other more pressing concerns. Anyway, someone made note of a bug in ATVTW (for M2TW) in which the Attribute Combat_V_Faction_Ireland was being recorded as incorrect. Gigantus reminded me that in the exe for M2TW/Kingdoms didn't specifically list the faction and religions for the Combat_V_Faction_XXX and the Comabat_V_Religion_YYY attributes. I already knew this was the case for the Combat_V_ZZZ attributes in Rome.
So I did an experiment, I create a trait with a custom attribute:
And a trigger to test the attribute:
Effect Combat_V_adfjeil 1
I gave the trait to a starting character in descr_strat, and checked his traits and stuff in game, and he had the first level of the BattleScarred trait. I did a second test by adding the effect to an ancillary (and leaving the trigger in EDCT), removing the trait and adding the ancillary in descr_strat, and again I started the game and he again had the first level of BattleScarred.
Condition Attribute Combat_V_adfjeil = 1
Affects BattleScarred 1 Chance 100
This is very significant as it allows 100% accuracy in seeing if a character has a particular ancillary, and unlike current methods this can be used for all ancillaries by giving them a unique Combat_V_ZZZ attribute.
This has left me with an interesting and answered question. How does the engine determine if the Combat_V_ attribute corresponds to an actual culture to give a command bonus?
There's also a hidden attribute that is recognized by the exe: FootInTheDoor, you can assign it as an effect to traits/ancillaries but I haven't figure out what it does.