Is Poison Supposed To Work This Way?

I have no item that gives a poison effect, only my chestplate "Seagazer" that gives -84 per 3sec poison nerf... yet, when I hit something, it hits it 3 or 4 more times with a replica of my weapon's damage - for instance 100 neutral 130 water damage while holding lunar spine, or 340 neutral damage with bob's mythic.

These are my accessories and gear total:

Ancient Restored Helmet (or something, it's from the purple and blue quest), Seagazer, Crystal, Stalagmites, Ring of Rubies, Worship, Squid Anklet, and Altum Spatium. I use Bob's Mythical Wand and Lunar Spine, so my weapon isn't applying poison either.

 

Do you have anything that might be doing wither damage to your enemy? That might be the problem.