Staff fighting vs undead really weird…

When fighting vs 1 skeleton its normal, meaning I need to pound him quite a while to kill him, but when fighting 4 or more of them they just die with a single hit. Am i supposed to be going on rampage or something..? anyone noticed it?

Hm, I notice that you can hit more than one enemy with your sword, but that would explain only part of it…

I've seen it many times, and always thought it was critical hits or some accumulation from perks. I've seen it against all creatures with all weapons, even ranged ones.

So I would say it is a bug. It definatelly doesn't sound like "by design".