Silver
We all know about the silver key spirits, but I assume that they're not all necessarily weak and some of them can be on par with the majority of the gold keys (the only ones that are surely out of their league being Leo, Aquarius and Scorpio) while some of them are useless in combat. A few of them will have mostly non-combat uses, but some will be really good in a fight. I assume that since their keys are so common and one spirit can have several of their keys out in the world their biggest weakness is that they have even fewer days they can be summoned than the gold keys since you may have to share them.
Iota-The Sword
Appearance: It would be a double-edged sword with a silver hilt. It glows sky blue.
Personality: It would need a lot of attention. It would be kind of annoying and finicky, but very ready to step up when its master is in trouble. It would talk a lot, even though it doesn't have a mouth-or any kind of face. If its master doesn't summon it just to talk outside of fights or ask how its day is going it would give them the silent treatment.
Abilities: It's a levitating sword with a mind of its own. It's very good in combat, even able to hold its own against several armed foes. It's limited by it's summoner though so it's only as fast or strong on its own as its owners magic power will allow
Navis-The Ship
Appearance: A boat, pretty much.
Personality: Doesn't say anything.
Abilities: It's a self-operating boat that's helpful for crossing water. It can grow in size but that quickens the drain on its summoner's magic power. Typically a small, wooden rowboat, but can grow into a huge warship with magic canons if its summoner has the magic power to sustain it.
Tucana-The Toucan
Appearance: A regular schmegular toucan.
Personality: Very uplifting. He gives motivational speeches in the spirit world and helps spirits with their self-actualization and positive self talk skills. He pushes everyone to be more confident and take risks. He uses his magic to help people with public speaking and confessing their love and things like that.
Abilities: His magic is Disclosure. He sprinkles orange powder when he flies that causes everyone around him to tell the truth in a poetic and/or motivational way. He can't control who tells the truth or not so it affects everyone. It can be used to get information out of someone forcefully or to help someone tell the truth in a positive way like asking someone on a date since it makes you speak so beautifully.
Vulpecula-The Fox
Appearance: She'd have black hair and wear a red and purple kimono. She has gold eyes, gold fox ears and gold fox tails.
Personality: She'd be very quiet and reserved.
Abilities: She uses fire and illusion magic. The power of her summoner equates to how large of a scale the illusions are and how powerful her fire magic is. She can turn into fire and dash short distances. She has a telepathic connection with her owner so they can choose and illusion without it being revealed to the person it affects.
Fornax-The Furnace
Appearance: A regular teenage boy with red hair and a red sweater with red pants. He has blue eyes and holes burned in his clothes. He has a small, square, metal furnace that floats behind him everywhere he goes.
Personality: He's very nice and speaks to his furnace more than people. He's very proud of his baking skills.
Abilities: His furnace has Fire Magic and he can command it to attack with blasts of fire and fireballs. He has no magic of his own or combat skill so he's not used to fight very much. He also has Baking magic. He creates magic baked goods. They're always the eater's favorite flavor and awaken a happy memory in their mind.
Cygnus-The Swan
Appearance: It shifts between being a black swan or a white swan based on whether it's light or dark where it's summoned. This could mean it could be nighttime, or in a dark room or in a place that's magically been made light or dark. Female in dark form, male in light form.
Personality: They don't have much of a personality since they make swan noises.
Abilities: In light form he can heal injuries and teleport himself and others short distances that get longer based on the keyholder's magic power. In dark form she can dispel magic, whether that be a specific spell or ongoing ability. With more powerful summoners, she can dispel the magic power in another person's body and leave them powerless until they absorb more ethernano. Using this ability drains magic from the summoner quickly though.
Auriga-The Driver
Appearance: An ornate carriage with no horse or driver.
Personality: None
Abilities: Can take the summoner wherever they want to go even if they don't know the way there. It's indestructible, though it can tip over. Has several secret exits. Uses very little magic power.
Lepus-The Bunny Rabit
Appearance: He'd be a young guy with hair that looks like bunny ears and an all gray school uniform.
Personality: He'd be very mischievous and crack a lot of bad jokes.
Abilities: He'd use Athletic and High Speed magic and employ that speed and agility to use during hand-to-hand combat. He can carry a couple people without slowing down noticeably.
Scutum-The Shield
Appearance: It would be a gold shield with a huge gem in the middle.
Personality: It's like Caelum so it behaves more like an inanimate object than an actual being, but the gem would change color like a mood ring. It's owner would understand what emotion that meant so if it turned blue they might say something like "don't be sad, you did okay" or if it turned red the owner would say "calm down, we still got this" while everyone else is like "wtf is this girl insane?"
Abilities: While it is a floating shield that can tank attacks on its own it can also use Barrier Magic. It creates force fields of whatever size is necessary to protect whoever the summoner tells it to. It also can create specific shields like shielding from light to make and area dark or making an elemental shield. It also has a habit of floating into someone and bashing them if it gets angry enough. Shattering its gem sends it back to the spirit world.
Canes Venatici (Canis for short)-The Hunting Dogs
Appearance: They'd be cute little wolf cubs with white wings on their backs. There'd be a dark brown, light brown, white, black and gray one.
Personality: They'd get into all kinds of trouble together but get out of it because they're so cute.
Abilities: They can track anyone or anything as long as they have the slightest scent to go on. It doesn't matter how far away the one being tracked is. Also, it's rare but if they get angry enough they can grow to normal size and it's never good when 5 flying wolves decide to get mad at you.
Sagitta-The Little Archer
Appearance: She'd be a young girl with brown hair tied in a ponytail and green eyes. She wears a green shirt, brown pants and black boots and she has a bow that's the size of her body. She has no quiver of arrows.
Personality: She'd be Sagittarius's younger sister but have a completely opposite personality. She'd be sassy, a lot less polite and criticize her summoner if they tell her to do something that won't work.
Abilities: She's a great archer like Sagittarius but isn't good enough to be able to stop bullets, hit fast-moving targets or fire more than one accurately. To make up for it she creates magic arrows. Some can cause no harm when they hit and just put people to sleep. There are scatter shots, ice arrows, fire arrows, shocking arrows and heat-seeking arrows if she can focus enough while aiming.
Musca-The Dragonfly
Appearance: A human woman with big purple dragonfly wings.
Personality: Kind, soft-spoken, helpful, empathetic, nurturing.
Abilities: Healing Water magic. Her water heals people it touches. She can make a water shield with it too. She can pressurize it to attack but it's not very powerful since she's not an offensive spirit.
Andromeda-The Sacrificed Princess
Appearance: She'd be a woman in a toga dress with a tiara on her head. She'd also be chained to a post. Or she'd be in her other form where she's made of fire and has demonic bat wings.
Personality: Her main form's personality wouldn't be important because of all the screaming. In her other form she acts like a feral beast instead of a regular spirit.
Abilities: Her screams of terror are powerful sound attacks. They're strong enough to break stone so using it on a person is pretty damaging. But she's chained up so she can only attack in one direction. She can be summoned after she's been eaten as well. When that happens her vengeful spirit fights and it has the power of flight and uses a pickax tied to a chain for combat.
Ursa Major-The Polar Bear
Appearance: She shifts between a woman with white hair and a silver outfit and an 8ft tall polar bear based on the situation.
Personality: She's a mama bear. She's extremely protective of her keyholder. She'd distrust most people they come across and in combat value keeping them safe over defeating the enemy. She'd get on them about wearing sunscreen and bug spray if they're outside and do a lot of cleaning and cooking when they're in the summoner's house.
Abilities: In human form she uses Ice Magic. She can lower temperatures and blast people with cold energy as well as manipulating the movement of shards of ice. In bear form she has standard enhanced strength, fangs, claws, etc. that you'd expect
Apis-The Bee
Appearance: A girl in a black and yellow striped outfit with black hair. She's always wearing a crown.
Personality: Extremely obedient. They'd actually not attack an enemy they're summoned to fight or do anything that would be common sense if they aren't given an order. They'd usually be summoned for housework or any kind of busywork, but they'd learn to fight if asked.
Abilities: Duplication Magic. She can create multiple copies of herself that increases based on the summoner's magic power from 3 to later 15+. She can also fire magic stingers from her hands that cause irritation to whoever they hit, but aren't very powerful. The clones don't have much skill fighting physically by themselves but if they overwhelm a target they're more successful.
Corvus-The Crow
Appearance: He'd be a guy made of pitch black shadow with wings on his back.
Personality: Very quiet, but when he does speak it's usually a solution to a problem nobody thought of or an unexpected joke. He'd be sad so many people are scared of him
Abilities: Darkness Magic. He can turn invisible & create and mold darkness and shadows.
Sculptor-The Craftsman
Appearance: A middle-aged spirit that carries around a magic chisel and a bag full of magic stones.
Personality: He's obsessed with his sculptures and takes out his stones to just admire them.
Abilities: His magic stones grow to whatever size he wills them to and the chisel magically turns them into whatever the summoner wants. He can make wolves, dragons, birds, golems or whatever Sculptor can imagine. After that he uses the chisel to animate and control them to do whatever they need to.
Phoenix-The Phoenix
Appearance: A phoenix made of pure white fire.
Personality: He'd go into long lectures whenever the summoner does something morally wrong and refuse to leave until he's finished. It can be as simple as j-walking and he'd talk about the dangers associated with it and your duties to obey the law as a civilian.
Abilities: Holy Fire magic. His fire doesn't harm people at all so he's not useful in combat, but it heals people and warms them up. It melts ice. It also purifies anything affected by any kind of negative magic.
Triangulum-The Triangle
Appearance: He's a glowing, magic triangle.
Personality: He'd be a super genius and very knowledgeable on magic. He'd be able to identify obscure magics and have information about foreign countries and their customs.
Abilities: Magic Reflection & Dispelling Magic. He can reflect magic spells of all sorts back at the caster or away from him and he can dispel magic performed on a person or object. He can't fight because he doesn't have hands and he can't dispel a kick to the face though.
Hydrus-The Hatchling
Appearance: It's a little baby water monster with big eyes and a head bigger than its body. It's made out of water and it floats around
Personality: It would make baby noises.
Abilities: Cuteness. That's not a magic ability, it's just from how it looks.
Pegasus-The Flying Horse
Appearance: It'd be a girl with white wings. Almost like an angel.
Personality: Very obsessed with being "in". Somehow she'd be able to tell current trends from the celestial world. She'd be mad when she has to travel somewhere that's not "in" because she doesn't want to damage her reputation. She likes to be current. (That's a joke because of her magic.)
Abilities: Holy Wind magic. She can summon wind and use it to transport herself and passengers wherever they need to go so long as it's possible for the current to get there. Wind controllers can intercept their travel unfortunately. She can also purify those afflicted by harmful magic.
