Blizzard have changed the 4-set bonus for the 10.1 armor on Windwalker Monks on the PTR.

Windwalker PTR (Source)

We have deployed a hotfix to the 10.1 PTR realms to adjust the Windwalker Monk 4-Set bonus. The new bonus is as follows:

Windwalker Monk:

(4) Set Bonus: Fists of Fury deals 25% increased damage to the primary target and increases Shadow and Fire damage you deal to all targets hit by 40% for 15 sec.

Developer’s note: This hotfix replaces the existing 10.1 Windwalker Class Set Bonus with a new effect. While we loved the fantasy of granting Windwalkers an additional spirit, we heard your feedback around the resultant lack of control loud and clear and are making this change as a result.