Well this is something I see a long time ago... Soulshot in mobs doesn't show the soulshot anim.
If mob have BOW, he show the soulshot anim, if isn't bouw doesn't show it.
I think time before l2jserver bug this in some re-work and never see the difference bcoz anyone report this like 9139813891 another things, the admins doesn't report a lot of details, this is one of them.