Grim Dawn: Skeletons causing meteor shower

I am playing Grim Dawn with all the DLC except Loyalist items packs. My character is a Shaman Necromancer (level 32) and I have no item granting meteor shower skill and no active constellation with that skill.

I noticed that when I summon my skeletons (Necro skill level 12) for a while they can use the meteor shower skill (after a while sometimes they stop doing it). I am sure of that because if I do not summon the skeletons I do not see the meteors. It started when my skeletons appeared "equipped" with armor, when they were lower level they appeared "naked" and the meteors did not happen.

In the skeleton skills popup I do not see any reference to that skill, just the usual damages and other stats.

I do not understand if it is a bug or I am missing something in the skill system.