Speaking of Slyphie in the CNJ class quests about how she was powering her spells, the form of magic she was using was technically a traditional WHM ability from earlier FF games, known variously as 'Sacrifice' or 'Martyr' (as it was known as a WHM merit ability in FFXI), where that character/player sacrifices some of their own HP (ala, 'life force') to heal another character/player by a larger amount.

Although it essentially was using her own aether to do so, it wasn't technically Thaumaturgury, as that's a different school of magic (which came about from funeral rites practiced by priests of Thal).