First off let me make it clear that I understand this skill isn't comparable to other skills that summon servants in the game, it's a bunch of skeletons spawning off corpses and attacking enemies randomly apparently and that's why I think this is a bad skill and not very well thought-out. I don't know if other necromancers like this skill, but I dislike it for some reasons that I'm gonna list next.
It's a totem
Requires corpses
In duration of the servants it stay in the middle of a swarm and a long lasting one
The skeletons don't focus on the necromancer's targets being hit by or hitting him
So to fix this problem I think it would be necessary a complete revamp of the skill, but this would never happen so what I think would be close to good is
Make the first skeleton spawn without need of a corpse
At least one skeleton at a time should focus the necromancer's target (I understand that making every skeleton attack one target would be too strong, even thought it can happen already)
And that's it. I think the skill deals good damage at least in PvE, don't get me wrong, but the way it works ruins it, like when there's no possibility of a corpse, the skill is absolutely useless and the Necromancer already has too many extremely situational skills compared to other classes in my honest opinion.