Arcane Random/Incorrect Drop

[onlyThEsHadowS]

Yesterday I decided to farm vomvalysts for quill standing. I discovered that they spawn from eidolon teralyst so i farmed it from them. I got a few lures with me and I farmed around 15 - 20 sentient cores. Upon returning to cetus I was given Arcane Momentum and an eidolon shard.

Not sure what to make of this I asked around and noone seemed to know why this happened. From what I know, that arcane only dropped IF you kill the tera. I decided to do this again and it happened again.(edit: i forgot to mention, i did not kill the eidolon, nor did i bring down its shield)

Im not sure if this is intended to happen but I'll at least report it.

note: I was playing solo, i even checked my party status. My pc is relatively slow (intel I3, nvidia mx150, around 2gb vram)