During 2's tonight I was mousing over some of my PvP gear during the preparation time when I noticed that some of my items with engineering enchants no longer had the "Not usable in Arena" text in the item's tooltip. I had orginally had the Spinal Healing Injector enchanted, but had no Mythical Healing Potions to use. So after the game I enchanted Synapse Springs, re-queued, and was able to use it during the game, gaining 480 strength for 10 seconds. I was also able to use it in rated battlegrounds afterward.
I also tested Grounded Plasma Shield, but was unable to use it.
I will test the Spinal Healing Injector / Z50 Mana Gulper when my partner logs back on, and will upload screenshots. Also will try to test out other enchants... Im really hoping the Mind Amplification Dish works!