It appears that Rending does not appear to be working as described. Ever since its rework, it is described that every 4% over 100% rending essentially gives a 1% damage boost. By this logic, going from 100% Rending on Ruthless Backstab or Uncanny Strike (Tier 3) to 120% (tier 4) should essentially give a 5% damage boost. After testing this thoroughly in the Meat Grinder, I discovered this is NOT the case at all. Your damage does not go up when your Rending goes above 100%. I have tested this on both Armored and Unarmored Enemies.
The only upside to Uncanny Strike Tier 4 is that the rending basically stacks faster, getting to 96% rending by the 4th hit as opposed to 80% at Tier 3.
Bear in mind I have only tested this on the Catachan Combat Knife. I have not been able to test this on other weapons such as the Dueling Sword. I don’t have too many other weapons with such Blessings so any help on testing this would be appreciated.
I did a quick search of the forums and didn’t see other posts regarding the issue, so I thought I should throw this out there.