Reduce target's X resistance by 10% (All dps classes)

[Gustuf]

"Reduce target's X resistance by 10%"

Can anyone elaborate on the meaning of the above statement.

I hear a lot of people on this and other forums are saying, "Debuff X is a 10% increase to damage". I don't believe it to be the case and I believe this is a popular misconception.

To me, from the way the description is written, I understand that it would reduce the amount of damage mitigated by that resistance.

Example, Boss mob has a 20% blunt/pierce/slash/elemental resistance (Hypothetical - no idea what the average resistance of a mob is; assumed lower). Player reduces its resistances by 10% (2% resistance). If one would normally hit for 100 damage, and 20 damage is mitigated by resistance, a 10% reduction in the mitigation would be a 2 damage increase. In this case, damage is increased by 2.5% {(1-0.18)/(1-.20)} for that specific damage type (blunt) for all players in the party/raid.

Does anyone else agree that this is the case or am I wrong in my understanding?

Thanks