After doing some testing, I do think cursed weapons can have a place without the need of being ultimate, but there needs to be an adjustment to the Death's Rush buff that you get.
- Buff be obtained on every killing blow
- Buff last 5s at a minimum, with maybe even a 7s duration
- Buff gives 12.5% PvE on Kill and 25% move speed, stacking 2x to give 25% PvE and 50 speed (I think giving the same PvE damage as the 180 set could be very strong, and makeup for the loss of attack of no-ultimate, but would have to do some more calculations).
- On kill, you're healed based on the % of Death's Rush to your Max HP (A skill that revolves around death should have some sort of HP gain tied to it. HP on kill seems like it can make sense. Another thought was having the buff grant Lifesteal, something like .4 and stacks 2x).
- Buff is lost if the weapon is not equipped (being able to get the buff then swap Weps to benefit could have some implications of being wildly OP.)
For 1v1 classes, this could be very enticing. For mages or anyone AoE, Waterbomb is still going to carry (don't get me started on the brokenness that is WB). To combat this, you could have some sort of "corpse explosion" that does a % of the mob's HP as damage (based on Death's Chance roll), but would need some serious testing since those damage numbers could get crazy, but who knows, maybe not with how WB is.
Just some food for thought. Personally, having a weapon that would be dedicated to leveling due to its ability is pretty eye catching. Stays pretty relevant and holds value since people are always leveling, and gives you that power boost without directly competing with "best in slot end game" Weps. And since it requires killing blows to gain, dungeon runs would still be using coral Weps (unless corpse explosion finds a way in).