Getting rid of Festering Curse is a very good idea imo.
As for what to replace it with, personally I don't think it needs to be something that increases their DPS or something to make them more powerful, in raid type situations at least. If you can remember my previous posts, I am not a fan of the raid thing anyway... but still. Necro's are still an 'ok' class even without the curse. They might not be the highest dps, but whatever. My point is that unless the other classes have all crept far ahead (I am out of touch with the game now), I personally think it should just be something designed with more focus on it being fun, rather than it being powerful. In other words, I don't think they really NEED anything, when it comes to raiding at least, and to some extent, grouping.
That leaves two more ways to focus your ideas. One is that you could think up some weird and wonderful ideas for what you could replace it with, and that would be fun. But calling peoples ideas half baked isn't going to do you any favors btw, you would need to have a big brainstorm and everyone would need to sit in a circle and hold hands. But thinking up ideas could be fun. I might put a few at the end of this pondering post if I'm still awake.
The second area you could focus your ideas on, is to address some of the class weaknesses which I think the class has has always suffered with - compared to others. I haven't played for a loooong time now, so not sure if the crappy situation with summoning mobs was fixed yet? If that was fixed then maybe I would see things differently. If it wasn't fixed, and is not likely to be fixed any time soon, then I would suggest an ability to help necros in those situations. In other words, to let them be able to fight summoning mobs like other classes can, without constantly being summoned and killed.
The biggest glaring weaknesses I can see to necros though, is their lack of AE potential, and the weakness of their pet. I am assuming that compared to the other casters, when soloing, they seem ok. In other words, druids and wizzys can maybe quad kite but necros can kill single mobs more steadily and with better mana regen so it kind of evens out. Rogues kick ass but have to sit and boringly recover health after a while. Etc.. And Necros also get some cool tricks like FD which some classes dream of. In other words, when soloing, I am assuming it's all kinda sorta fair, ish.
But when you compare classes in duos, I think things all go horribly wrong, and on a server like this, that is a big issue imo. I would even wonder if Necros are maybe one of the least favoured duo partners? Obviously other classes are weak in the WRONG duo, but at least they have the potential to be really outstanding in the right duo, but with Necs I'm not sure there is really anything you could pair them with, to make the pair extraordinary. Take a Rogue for example, not only is their DPS great, but when well geared they can also tank several none raid mobs at once. I've seen them running around in Seb, pulling entire rooms at once. So match up a Rogue with a healer and you have a leet combo that can do some crazy shit. Then take Druids, they can heal and they have good AE spells. So match up a Druid with something like a Pally and the other guy can round up mobs in big groups and then the pair can smack them all down in big groups. Wizzys likewise. Monk, well similar deal to the Rogue if not even more overpowered thanks to their FD etc. Chanters, hmm, I'm not even sure if they are ever part of 'crazy shit' duo's? But if not, maybe they need to be looked at too.
Anyway, that's my theory. Everyone is doing crazy shit in duo's except Necros, that's how it sometimes felt to me at least. Again, when playing 'normally' (soloing or grouped or in raids) I would pick my necro over anything. But when doing crazy shit with a duo, there are some great duos that work really well, and as far as I know at least, Necro is never a part of that. And it never changes with your tiers either... Unlike say monks or whatever, you get well tiered monk and shammy and you can start working your way through low tier raid content quite comfortably. Even with high tier gear, the Necro doesn't really get anything out of it. All that really happens is that their mana pool and survivability increases which is pretty much useless outside of raids.
What makes them weak in these situations? Imo it's the pet and lack of AE. First off, the pet. The Necro cannot AE snare unlike the Dru/Wiz, so they can't kite (except singles which is a waste of time). So they NEED the pet to do anything. They can root/rot single mobs of course, but again, singles is a waste of time, and if the mob can summon, fugedaboudit. So they need the pet, but there is hardly any difference between a fresh level 65 and a tier 99 uber. The pet is still a one mob guy. You can pair the Nec with a wizzy or Druid but unlike any of the melee classes, the pet is never going to be able to round up groups of mobs and tank them while the other person AE nukes them all down. It's just too weak and not a good enough tank. And in fact, it's not even good enough to be a viable tank against one mob in most 'crazy' type situations. It might be ok against standard mobs in seb or something, if you are paired with a healer to keep it up, but put it up against any tough named and it just gets eaten, even if it has raego. A good healer can 'sometimes' keep it alive, but only by blowing their mana faster than they have ever before, and if the mob can flurry or something like that, then the pet is screwed. So basically, the pets suck at being anything other than a useful aid when soloing and a kind of walking dot in groups etc. So you could maybe consider 'fixing' the pet to make it able to AE aggro and tank a bit better. Necros have always been crying out for multiple pets anyway... The mage gets a few to choose from with cool tactical effects, and the necro gets 1! I remember when they came up with the monk and rogue pets and I thought they were finally going to give Necros what they always needed, but those became useless once you outleveled them. So that is something that has been a long time coming. Keep the skelly as the dps pet, maybe even lower their hp a little bit or something. Then have a armored zombie which is their tank pet. It's dps is hopeless but it can AE taunt really well and safely aggro against up to say... 4 mobs. It's still no Pally box but then the necro still has all their spells too.. Then maybe have a third pet just for fun and to round things off, which is a caster and works like Zaela described. Maybe it lifetaps not only to keep itself alive but it also transfers health to the group too, and maybe it regularly nukes (or AE nukes) to make up for Necros long standing lack of satisfying nukage. Anyway, that's the pet.
The other one was the lack of AE. Again in duos, the necro still can't really do anything better than when they are solo. For example a pally could round up 25 mobs, and the necro is still forced to handle it by sending their pet against just one mob and starting their slow ass dot rotation, on just one mob... Or blow all their mana spamming their one nuke, against just one mob.. I'm sure there are some situations where a necro could be good as a duo, but for now I can't think of anything so I'm going with this. They are supposed to be a DPS and all the other dps's can either AE or tank. So to rectify this, perhaps give the Necros a leet AE as their AA. Perhaps a good dot similar to their others, but it works on any number of mobs in the area. That's pretty much the end of this suggestion, but you could elaborate and maybe make it more interesting. Like maybe the dot is actually an improved version of Splurt so starts off doing very little, but if you are patient enough it ends up spamming huge damage for several seconds. Or maybe it's quite a weak dot but it stacks with itself. So you have to use the ability and then wait 15 seconds and then use it again to stack the dot a second time, then use it again to stack it a third time, and 4th, and 5th etc.. So it's effort intensive, and takes a lot of time and focus to pay off, but eventually it's doing huge damage. Or maybe make it even more interesting, each click stacks the dot but also subjects the necro to a shadowstep too. So be greedy and stack it one too many times and you shadowstep off a cliff, or in to a group of mobs or something. Or seeing as even that could be controlled by having your partner always pull to a small room safe room, perhaps have it so that each time you stack the dot, you get a random negative effect on yourself too, taken from a pool of several possibilities. So the first time you stack your big ae dot, you also get rooted. On the second stack you also get hit with Scourge, so you quickly need to sit and mem cure disease to save yourself. When you stack the dot the third time you are hit with an ice comet and you quickly need to lifetap your health back before you bring mad aggro to yourself. And the fourth time... you get blasted in a random direction, luckily you hit a wall which saved you. Will you go for a fifth time? You want that huge AE dps but zomg what could happen?!! You do it and you get me charmed and start casting stuff on your buddy or on yourself. Doh. But it was just as likely to hit you with a dispell which would have been ok. Maybe even throw in a few beneficial effects too, a little heal, a buff, etc, so doing the huge AE dot thing is great for XP but it's also a verging a bit in to russian roulette ville.
Anyway I think I've said enough for now.