Ahh I see you found an answer in general. I think when it is close to an existing effect, it is safe to just assume it is the existing effect.
Sorc instakiller isn't a good build imo, because it leaves heal, tank, and dps, which a PUG group will generally fail to fully fill with a powerful character with 1-3 powerful characters per group and 1 of those being a sorc instakiller. Make that sorc an instakiller + heal or tank or dps, and that's a good build. It's like how
monks were complaining even before QP nerf because that's all they built around. Instakiller isn't a role, so QP monk failed, while this is heal + tank + dps trinity, so it doesn't. fail. Or see how every instakiller build out there complains about a lack of dps (trinity role). It's ok to have instant kills, feel free to slot in some assassinate if you want, but if you go all in on it, your build will be less powerful for pugging than a trinity build, unless you consistently play in pre-made groups where trinity is already covered.
With Fan of Knives nerfed after a decade, looks like they are removing any no-save ranged AoE dps ability that can be stacked on top of ranged AoE dps attacks. On a plus side, now that Fan of Knives is a purely melee or ranged power ability, it may work like Ki Bolt now and be even more useful in its nerfed form than its original form. Just stack ranged AoE attacks (Head shot + inferno + epic AOE ranged attacks), and use draconic + FoK for mantle for single target?
Edit: looks like they deactivated it as a spell. No on spell hit effects affect Fan of Knives SLA now, making it broken for everyone.