[zenith]

The stacking probably needs a primer here.

If you have a +6 for a stat and add a +1, you only get the best bonus.
If you have a -4 for a stat and add a +1, it improves it to -3.

As for the amount of damage resisted, I believe it is working as it should. I'll review the data on live after more attacks and compare them to older battles with previous armor. I may increase it's effectiveness if I don't see an overall minumum 15% increase in damage resisted. At the current time though, the numbers are inconclusive since there aren't enough battles to get an accurate reading.