The word "Characteristic" and its interaction with abilities

[Kirjava13]

When warscrolls, abilities, spells or anything else reference a "characteristic", are they referring to the unmodified stat?

For example: on the Dreadscythe Harridan/ghost Hormagaunt warscroll, the ability, "Harrowing Shriek", has the following wording:

Quote

Subtract 1 from hit rolls for attacks made by enemy models within 3" of this unit unless they have a Bravery characteristic of 6 or more.

Emphasis mine.

Say a unit of Dreadscythe Harridans are fighting a unit of Ironjawz 'Ardboyz, who have Bravery 6 on their warscroll. The Nighthaunt allegiance ability, "Aura of Dread", subtracts 1 from their Bravery, making it 5. Which number is used for determining whether "Harrowing Shriek" is in effect: the modified or unmodified Bravery characteristic? Do the 'Ardboyz get -1 to hit, or not?

A second example: the Nighthaunt spell "Spirit Drain" has the following wording:

Quote

If successfully cast, pick an enemy model within 18" of the caster that is visible to them. Roll a number of dice equal to that model's Wounds characteristic. For each 6+, that model's unit suffers 1 mortal wound.

Emphasis mine.

Say a Nighthaunt wizard successfully casts "Spirit Drain" at a Treelord Ancient, who has taken some damage and is down to 8 wounds. Which number is used for determining how many dice are rolled for "Spirit Drain": the modified or unmodified Wounds characteristic? Does the Nighthaunt player roll 8 or 12 dice?

[TheWolfLord]

It entirely depends on the wording of the abilities in play.

In your first example, Aura of Dread subtracts 1 from the Bravery characteristic so does reduce the Ardboyz Bravery to 5. 

In your second example, Spirit Drain rolls 1 dice for each wound on its targets wound characteristic. Wounds taken are not modifiers to the wounds characteristic so when targeting a Treelord Ancient the Nighthaunt player would always roll 12 dice for that spell regardless of how many wounds the Treelord Ancient had taken.