I feel like that writing some thing like that would trap the authors/Lore team. If killing an ascended means killing an Idea, or concept. Than Humans have killed Ideas and concepts, other ascended have killed Ideas and concepts. Hell, Myisha got a group of them together to specifically cause the death of some of the ascended. Which means as a whole Runeterra is way shittier than what it used to be, since I believe that is was mentioned that there where thousands of ascended, and most of them are dead.
The ascended that originally had the Chalicar(I forgot her name) was revered by all other ascended so much so that her weapon became a powerful symbol that was capable of making the fallen ascended put aside their differences long enough to hear each other out, at least before trying to take possession of it. What idea or concept she is must of been so profoundly good that her death would probably be seen as the reason as to why the Ascended became Darkin, and the collapsing of the Shurima Empire was just a side effect of her death.
Wouldn't it make more sense if the ascended are a reflection of an idea or concept, or just a representation instead of being the actual idea or concept?
The Aspects already have the narrative realm of being a living Idea, but also everything they do or say is completely within the realm of the idea they are the aspect of. The aspect of twilight is all about change, so twilight has to always be doing something new, something different, always looking for that new interest. I doubt the aspect of twilight could even stand being in a static environment as that goes against their very being. The protecter on the other hand can, and will find beauty in a static environment and would do all he can to preserve that environment in time of change.
So that would make the Aspects the Ideal, the purest expression of what they represent. The Idea. A dod.
The ascended on the other hand are the beings that have an affinity for their concept, they valued something so much that they made it a huge part of what they are, but they are not limited by that idea. Take Nasus before his ascension, his brilliance was recognizable from a young age, "he read, memorized and critiqued the greatest works of history, philosophy and rhetoric within the Library of the Sun before he’d seen ten summers."(From the bio of Nasus) At 10 years old he had become an amazing scholar, long before he became a bad ass military tactician and commander. So when he was close to death and performed the ascension ritual, his values where so close to being the purist form of intelligence and knowledge that he was capable of ascending and had his values for knowledge and intellect turned up to 11 (godhood).
So than we can see that an ascended embodies an Ideal long before the ascension happens. They live it, they breath it, but they are not restricted by it. They are the letters that make up the word that is the idea. A demi-god.
