Note that they reduced defense from Blade Barricade by 3%, so the Single Saber Mastery 3% defense is really just bringing us back to the same amount of defense as before.
A bit overkill on threat generation, at the cost of a bit too much damage imo. i.e. they should have buffed our threat a bit less without touching our dps. I suspect pvp is the reason for the overall damage decrease in immortal.