On my dexer for example curse lowers my hp by ~4, my dex is high enough that my swing is affected, and mana by just a few. Talking about lowering all stats, well bless raises all stats, is that powerful too? I gain more stats with bless than I lose from curse.
Its not the stats that make it powerful, that's just the icing on the cake. Take a warrior using a 100% Cold damage Heavy X bow. 100 tact, 100 anatomy, 100 Damage increase.
Pre Curse hitting for 19-23 Damage
Post Curse Hitting for 25-30 Damage
Slap Hit Spell and hit Velocity onto it and you are doing running shots that can be almost on par with an armor ignore every 2s with a 211 stam suit and enough ssi. And remember the hit spell is now doing 33% More damage as well.
That one spell can increase the base damage done the same amount as ~ 100% Damage increase on your suit. And because it lowers the resists its literally a damage modifier to everything other than physical attacks.
Enemy of one at 120 Chivalry is only 16% Damage Modifier and lasts 8 SECONDS. And comes with increased damage to you from other targets.
Evil omen is a 25% Damage modifier (Can make armor ignore go above cap though), but is only a 1x effect.
Corpse skin is Useless
Spell Plague isn't even in the same ballpark.
Sleep has diminished returns.
So yes, a spell that is literally a 33% Damage modifier, lowers all stats, can't be resisted even without full Eval, no diminished returns, and lasts for more than a minute, if you have no way to remove, is powerful in my book.
Now, no where in this have I said that curse needs to be adjusted or changed. Only that it is a powerful spell and to take its versatility and effect into consideration with the apple timer. I love curse, I love players who underestimate curse, if I could I would fit enough skill on every template to be able to use curse scrolls because honestly it offers the largest increase in my damage output for everything other than Ai's for the minimum amount of skill invested.