This question came up today in a game against my dad.

Dracula's Blood Armor reads:

BLOOD ARMOR: Dracula can use Impervious. If an opposing character took damage from his attack since its last turn, this power can't be countered and reduces damage to 0 on a result of 4-6.

My question is what does it mean that it cannot be countered? Does this just mean it cannot be outwitted?

The scenario where the question arose was he had Blade based against my Dracula who possessed Blood Armor. Dracula had hit Blade the previous turn so I was able to use the 4-6 and that is also when the "this power can't be countered" came up. Blade used blades, claws, fangs with exploit weakness and hit me for 5. The way we played it was that Dracula had to take the straight 5. Later we had the discussion if the exploit weakness should have worked because of the "this power cannot be countered" verbage.

In short, is exploit weakness considered countering this power or is it something else? Should have Dracula been able to use his Blood Armor?

Thanks.

"Countered" usually refers to Outwit, but there are special powers that can also counter powers and abilities. Exploit Weakness deals penetrating damage, though, which is not the same as countering.

Exploit Weakness and Psychic Blast = Penetrating (damage isn't reduced)
Outwit = Counters
Pulsewave = Ignores

If Vamp has fed recently, then you can't counter it (outwit his defense). But, it can still penetrated, as Impervious reduces to zero on a 5-6 (or in this case 4-6). And of course Pulsewave still ignores it.

Makes sense.

So penetrating damage doesn't mean it is countering or ignoring then? For example, Ulik from HoT has that special power where damage is reduced to 1 and this power cannot be countered or ignored.

Correct. It's important to look at the exact wording of a power. Countering, ignoring, and reducing are all game terms with specific definitions, and something that only mentions one doesn't apply to the others.