Yes, all magic users draw from aether and the difference between them is the school and techniques used to cast something. A conjurer will not proceed the same way as a gladiator with Flash or a monk with chakras for exemple.
Arcanists do indeed use sigils and geometric patterns they draw on a book to channel their own aether into finely tuned spells, or to summon aether made entities called carbuncles (also classified inside the higher genus "elementals" like faeries, spriggans or elementals, if I'm not mistaken, I don't have the lorebook with me right now).
Conjurers channel the aether of the land around them through their canes or wands: Nature's bounty, borrowed from elementals and whatnot through prayers and stuff. This is a moogle art originally, taught to Gridanians, but other forms of conjury and healing exist across the world, like ishgardian chirurgeons or ala mighan shamans. Conjury is mostly categorized into two main fields: healing and curative spells, and elemental spells (earth, water, fire, ice, etc, some of them like fire probably harder to draw upon depending on the land around, and frown upon by gridanian conjurers).
Thaumaturges channel their own body aether reserves (vary a great deal depending on the individual, some have almost none, some have plenty) into the gem of their staffs, channeled through the aether conductive materials of the staff itself, like bone or electrum (gold does the opposite though, it's insulating). They burn quickly through their own limited aether, but can regen it better, especially through the Coco brothers school of thaumaturgy which implies swap between astral and umbral elemental states, but that's only for thaumaturges of the newest generation teached at the Ossuary in Ul'dah. Older thaumaturgy is rather different, and other cultures can also have their own flavor. Thaumaturge magic is elemental and can be mostly comprised of all the elements, even if the Coco brothers only use half of them (fire ice and thunder).
Black mages draw their aether directly from the planet indeed, and considering the raw, powerful energies implied, if they don't have a gem of Shattoto with them (the soulstone), their most powerful spells will cook them from inside. White mages also draw their aether from the planet, and wether their method is more gentle or if the soulstone is also mandatory just to even cast white magic spells, is left to speculation. I suspect the later considering the WhM 30-50 quests, where the soulstone has to be specifically bestowed by elementals to the WoL so that they can access the arcanes of that magic, like padjal do.
Astrologians draw their aether from constellations and stars yes. These are apparently powerful sources of magic and can be called upon by trained sharlayan astrologians. A personal theory of mine is that ast magic is actually purely astral (diurnal) or umbral (nocturnal) magic, which gives aspected spells like aspected benefic and whatnot, but that's not specified in the lore per se. Astrology is actually in essence a time magic, using various time distortion and manipulation effects to change the states of things, or steer future possibilities to their will.
Red mages channel their aether exactly like thaumaturges/black mages: through their swords that act as staffs, and the gem at the top. While they can definitely draw upon the land like their white and black mages ancestors can, they refrain from doing so mostly by personal ethics, considering how the War of Magi leaded the world to the 6th Umbral Era. Their swords also act as special caralysts forged to channel their specific blend of white and black magic into potent spells, without having to draw from the land.
Carbuncles are mostly what you described yes. Egi and Faeries don't make exception and are in essence similarly created. Faeries just tend to exhibit more personality and intelligence (close to Spoken/humans, where carbuncles are closer to animals). Egi are infused with primal essence that the summoner has to have basked in before being able to summon them.
Arcanists do indeed use sigils and geometric patterns they draw on a book to channel their own aether into finely tuned spells, or to summon aether made entities called carbuncles (also classified inside the higher genus "elementals" like faeries, spriggans or elementals, if I'm not mistaken, I don't have the lorebook with me right now).
Conjurers channel the aether of the land around them through their canes or wands: Nature's bounty, borrowed from elementals and whatnot through prayers and stuff. This is a moogle art originally, taught to Gridanians, but other forms of conjury and healing exist across the world, like ishgardian chirurgeons or ala mighan shamans. Conjury is mostly categorized into two main fields: healing and curative spells, and elemental spells (earth, water, fire, ice, etc, some of them like fire probably harder to draw upon depending on the land around, and frown upon by gridanian conjurers).
Thaumaturges channel their own body aether reserves (vary a great deal depending on the individual, some have almost none, some have plenty) into the gem of their staffs, channeled through the aether conductive materials of the staff itself, like bone or electrum (gold does the opposite though, it's insulating). They burn quickly through their own limited aether, but can regen it better, especially through the Coco brothers school of thaumaturgy which implies swap between astral and umbral elemental states, but that's only for thaumaturges of the newest generation teached at the Ossuary in Ul'dah. Older thaumaturgy is rather different, and other cultures can also have their own flavor. Thaumaturge magic is elemental and can be mostly comprised of all the elements, even if the Coco brothers only use half of them (fire ice and thunder).
Black mages draw their aether directly from the planet indeed, and considering the raw, powerful energies implied, if they don't have a gem of Shattoto with them (the soulstone), their most powerful spells will cook them from inside. White mages also draw their aether from the planet, and wether their method is more gentle or if the soulstone is also mandatory just to even cast white magic spells, is left to speculation. I suspect the later considering the WhM 30-50 quests, where the soulstone has to be specifically bestowed by elementals to the WoL so that they can access the arcanes of that magic, like padjal do.
Astrologians draw their aether from constellations and stars yes. These are apparently powerful sources of magic and can be called upon by trained sharlayan astrologians. A personal theory of mine is that ast magic is actually purely astral (diurnal) or umbral (nocturnal) magic, which gives aspected spells like aspected benefic and whatnot, but that's not specified in the lore per se. Astrology is actually in essence a time magic, using various time distortion and manipulation effects to change the states of things, or steer future possibilities to their will.
Red mages channel their aether exactly like thaumaturges/black mages: through their swords that act as staffs, and the gem at the top. While they can definitely draw upon the land like their white and black mages ancestors can, they refrain from doing so mostly by personal ethics, considering how the War of Magi leaded the world to the 6th Umbral Era. Their swords also act as special caralysts forged to channel their specific blend of white and black magic into potent spells, without having to draw from the land.
Carbuncles are mostly what you described yes. Egi and Faeries don't make exception and are in essence similarly created. Faeries just tend to exhibit more personality and intelligence (close to Spoken/humans, where carbuncles are closer to animals). Egi are infused with primal essence that the summoner has to have basked in before being able to summon them.
Balmung:Â Suen Shyu
