Phalynx of Humility

The phalynx does not fetch, though it is not known why this is.

There are two different methods of obtaining this mount:

You can purchase it from the Kyrian Covenant Renown Quartermaster, Adjutant Galos, for 5000 reservoir anima and 100 grateful offerings. This is a very costly method but is guaranteed.
You can receive it as a low-chance loot reward from the Penitence of Purity covenant activity. You first have to activate your covenant's Anima Conductor and set it to the Temple of Purity. Then proceed to the Temple location, pick up the Burden of Penitence (which will be nearby and appear as a yellow dot on your minimap) and avoid moving patches on the ground to reach the Penitence chest and open it. Currently, if you use a vehicle mount (such as a vendor mount), you're immune to the patches on the ground. You can open this chest daily.