Taking Massive Damage When using Spirit Blade

I recently got Knight Enchanter and I've been trying out the sprit blade ability (with the barrier regen, etc). Every few battles there is a sound like an explosion when I hit a monster and my character takes massive damage and usually dies. At first I thought this was just bad playing on my part but this is happening with several different types of enemies that simply can't hit this hard. Recently i was taken to very low hp (couldn't see green at all) from full barrier and health killing one of the little green spirits. There were no other monsters in the area. The moment it died I took huge damage.

Note: I do not have friendly fire on, I even turned this on and off again just in case. I’m playing on normal difficulty and had not had this issue at all until I started using spirit blade.

Has anyone else seen or heard of this?  

--- So it seems it was being caused by some sort of bug with the custom armor I had made. I changed armor and the issue went away.