I've been noticing this for awhile, surprised I haven't seen it brought up. It seems when a Mark is applied to someone, their armor and spell resistance are lowered instead of giving penetration to the Nightblade alone as is advertised, which wouldn't show up in the targets character screen.
Here's the wording in the description:
'Marks a target for death. Player's attacks ignore 75% of target's Armor and Spell Resistance, but the target's attacks ignore 75% of player's Armor and Spell Resistance.'
What I interpret from this is that both players should get a buff for 75% armor/spell pen against the enemy, not a debuff to reduce their armor/spell resist by 75% which is how it seems to be implemented.
As it is now, whole raid groups (or pvp zerg groups) will benefit from one Nightblade's mark, which seems like a much stronger mechanic than is intended. Anyone attacking reaps the benefits of this incredibly strong armor/spell resistance reduction.
This transforms the ability from a strong but counter-balanced self buff to a virtually no-consequence raid wide support ability. It also makes getting away from a marking Nightblade who's in a group quite bothersome :P
Furthermore I've noticed that two separate Nightblades can mark one target for 140% reduced armor and spell resistance, leading to the marked target simply having 0 armor and spell resistance to anyone who attacks them until the minute is over. This screams unintended to me.
Anyone else noticed this oddity? Or can prove to me that the situation is not how it seems and is working as intended?