I got this thing early in Act 1 on my berserker and wore it all the way through about halfway through Act 2, even though it had terrible random stats and terrible rolls on enchantments. I don't remember actually seeing it ever activate either, despite my character always being in the action and getting hit a lot, though maybe it did in huge fights and I just didn't know what to look for. I finally replaced it.
It seemed pretty lame to me, at least with the rolls I got on it, but it's definitely neat to have unique items so early in the game that are truly unique in their effects, unlike D3.
I have this ring too, and it has a socket but I couldn't put anything on it. When I drop the socketable nothing happens, it just swaps the ring into my cursor, just like if it was a regular item. Anyone notice this? Wondering if it's a glitch or something amazing is supposed to go there to make the item better.
On the socketable description you should notice it says "requires item level X". In the upper right corner of the item you should see a number that marks the items level. If that number is lower than the socketable, they swap. This is why you haven't been able to place it in the item.