Sedna is the 6th largest body beyond Pluto's orbit. Because of this, I like to interpret Sedna along with the other
"Seven Dwarfs" or the seven largest bodies beyond Pluto (Eris, Haumea, Makemake, Gonggong, Quaoar, Sedna, and Orcus) which all deal with more abstract long term cycles (to a degree beyond even the "generational" planets Uranus, Neptune, and Pluto). Sedna's glyph exists as an official Unicode character (see above) so even some standard non-astrology fonts can display it.
Like the major planets, mythology gives strong clues to the meaning of Sedna and the other Dwarf planets or Dwarf planet candidates. In general, as Sedna's story suggests, Sedna is about trauma, victimization, and emotional turmoil. Positively, Sedna can be about acceptance, healing, transcending traumas, turning challenging experiences into strengths, and learning to integrate and be a steward for the depths (just as Sedna became caretaker for the creatures of the sea) even if we don't want to at first. In this sense Sedna is somewhat similar to Chiron the wounded healer. However, being more abstract and generational, Sedna can cover group traumas such as those related to race or gender, and even more abstract spiritual traumas such as that of being physically incarnated or "coming to this planet" in the first place.