Ferocity support doesn't work at all

Ferocity support does not give any attack speed, tested multiple attacks, tested with and without the Thrilling Chase passive, skills attack with the same speed. (frenzy charges are consumed though).

whirling assault also no have any speed increases from ferocity

Well I tested several different attacks.

However, please keep in mind that whirling attack has this "+1.4 seconds to Total Attack Time" which is not subject to attack speed, so if you plan on basing your build on that skill even working ferocity support will help very little with total attack time.