About Reaping Strike, how about making it generate more threat and add a trait to make the charging instant whenever you use an encounter or daily power? This way tanks have a way to quickly build threat on groups of mobs, and makes Punishing Charge more attractive to boot. I'd also swap Slam with Avalanche of Steel, like…
(Sorry for the long post ahead.) I confess I have mixed feelings about the whole buff/debuff concept being thrown out of the window, but this way is probably better than the craziness from before. That being said, I feel like the rework needs small tunings in a lot of places to really come together. Arbiter seems a lot…
Have you tried disabling Postprocessing and/or Screen-space Ambient Occlusion? Occasionally they bug out (for me, at least) and use way more resources than they should.
It is, however, a 25% recharge speed increase, which is intended since percentage cooldown reductions works pretty much the same way across all classes. You'd be better off asking for a tooltip change, I think.
The feat is most likely working correctly. Cooldown reduction in NW works by dividing the base cooldown for (1 + reduction percentage). So your 20 base cooldown becomes 20/(1,25) = 16 seconds, as your second last print shows.