https://elanthipedia.play.net/Sect_spell_affinity

This page is up to date. Monks do get potency upgrades to Moonblade at slightly lower moon power levels. It's not really that great of a perk. I would personally rather have the longer duration that other sects get on their spells put on Moonblade rather than the potency differences or go back to Monks getting the Moonblade upgrade at even lower potency (straight moderate level) that used to be in effect.