Hibiki's power is actually a holdover from her short life as a Human. The closest equivalent to what her power can do is found in Macross 7.
Of course, sometimes it lets the listener feel what she's feeling. She herself doesn't realize it yet, but she's sad.
I still don't have Minako's all hammered out, she's a harder one to read.
As for the Special Abilities, I always saw them as specific talents that anyone can have, but they just happen to be particularly predisposed towards such a thing.
For example, Alchohol Tolerance and Animal Magnetism. Some folks just aren't born with traits like that.
Take me for example, I'm innately good with animals by default, no special training was needed for that.
So Skills are like things you train to get better at, while Traits/Special Abilities are something you're naturally born with.
Also, I have no qualms about calling the special items whatever. I've used Artifacts as an interchangable term anyhow.
I personally prefer the term "Equipment" myself, but in saying that gave me an idea, why not have, for example, the name be "Special Items" and then have sub categories for each type of item. For example, Tenshi's Sword of Hisou would be under the Relic's Category, Marisa's Mini Hakkero would be under One-of-a-Kind Items and so on, and players who's characters have items on them, like mine does for example, would have to say what category each item goes into and describe what each item is used for and does if it also has a function of some kind, and if any of their characters items have a specific name they refer to them as, they would just refer to them as said name rather than "Grimoire" or "Staff" or "Sword" or whatever
.
For example, Yuzuki has a Staff (still haven't designed it yet :V), a Grimoire, and a small pouch. The Staff goes into the "Magic Equipment" Category, and she uses it to help Channel and utilise her more powerful spells when in combat or Spell Card Duels, but also uses it similarly to how Marisa uses the Mini-Hakkero in Magical Experiment's and Research, only Yuzuki uses her staff to help enhance her ability to gaze into Deep Space among other things. The Grimoire goes into the "Magical Books & Scrolls" Category and she uses it mainly for writing down notes in her Astronomy Research, though she does have a section of it dedicated to Writing Spells and Spell Card idea's down. Now what makes Yuzuki's Grimoire unique is that it, whenever a Page is ripped out, another page will appear in the back of the Grimoire to replace the torn out page, meaning that the book will never run out of blank pages to use. The Pouch goes into the "Bags" Category, her pouch doesn't really have anything special about it, she generally uses it as a purse/wallet, only instead of money, it usually contains some Spell, Spellcard and Magical Experiment ingredients for on the go, although it does have a feint magical aura about it due to all the magical items that have been inside it over the years.
Well that's the gist of how the Item categorization could work, though it's just an idea I had that I thought could be useful? But what do I know, I haven't even come up with my characters personality yet. :V