Is the meritocracy /within/ the magical underpinning of the throne or is the candidate's evaluation-on-merit in conflict with the _magical_ checks and balances of the throne?
Extending the issue further, in a world with such magical permeation, I see that pretty much all social and political 'rights' would need to have a magical underpinning. IOW if you want to give your populace Magna Carta-type rights, there needs to be a magical reason for it.
There will be a magical reason for the upper tier structure (King, Heir, Guild Leaders, Major House Leaders) which will be tied to a defense grid of some kind protecting the land from the outside Danger. But the human rights and general system balance will be a product of the founding badasses that set up said magical defense grid (something I need to delve into more). Similar to the US founding fathers, they will have specific views about how a person should use and can abuse power, so they were setting up a system that they hoped would mitigate some of the dangers and abuses they were familiar with.
The founding idea behind the Monarchy is that Family is important, but not due to Blood. Rather its the Idea that children raised to a particular role in society will be better suited for that role (like how scientist parents often spawn scientist children becasue they are exposed to it from an early age, and can benefit from the accumulated knowledge of the family. Higher up that also include accumulted wealth and magical artifacts, but the core is that the Family unit (a large, extended family at all levels) is your shelter and support throughout your life. Adoption and fostering will be common, but the social norm will be to go off to a guild school with the intent to come back and use what you learn for the benefit of your Family, usually by applying whatever skill and power you learned to the family business.
Why separate them?
As I see it, social pressures within a world with your magical framework can NOT be modeled by simple easy principles taken from our world. Guild systems, for example, are great for those who do in fact reach mastery and eventual emeritus status- but how does everyone else retire or invest or provide for themselves? Mass production (or mass resource exploitation) makes both retirement and investment a lot simpler but how does one do mass production when production is based on individual effort (of sending the brain into mindmeld with some cosmic element)? It would be very, very simple for a world like that to descend into a magic-production-slavery mode for a lot of the same reasons cotton-crop slavery, sugar-crop slavery and pre-industrial-mining slavery existed. Anne McCaffrey's Pern didn't go down this path because she essentially made each Hold into a need-based commune (and we can definitely read dragonriders as culturally analogous to Party members).
They are not separate, i just listed them to be inclusive of the forces I want to have on stage.
If I keep the population density low enough, and the level of "technological" development in line, I think it can be made to work. I am pictureing a setting similar to the Old West with magic swords; frontier land in the midst of an early industrial revolution. Settlements will be spread out, with hostile wilderness between. Magic and magic items are common, but at that level; some local made by craftsmen, others shipped in from urban area's with new industry. Magical energy is literally the currency (stored and traded in small objects, but more in the old school sense that it is just a useful common ground for barter trade.
Previously the guilds were very "old school" in the secrets and showy magic. The aging king changed that. He was a powerful Pattern Mage who instituted a system of accreditation. This let more people from the days of secret lore and disconnected magic Circle to a more cooperative place. Pattern Magic ties various magical processes (which may or may not be cast by the same person) into a complex working whole. The King instituted a system that lets anyone with the ability get credentials as a Lvl 1 Fire Conjurer, or maybe a a person can get credentials as a Grade 2 Fire Source; then regardless of whether they were initially trained as an Elementaist, a Druid, Magus, etc., they can be plugged into the spell and serve the needed function. The Industrial revolution was possible because of the idea of Interchangeable Parts. The accreditation system provides a standard to allow interchangeable Casters. This leads to a much more widespread practice of communal workings, giving industry a chance to take root. But resources will be scarce enough to prevent too big of a mass market explosion.
Exploitation is always a danger, and the hierarchical society makes it moreso. Some of the magic can mitigate it, like the cotton gin making large scale cotton slavery less economical. But there will be a good deal of room for evil people to do evil things, as always. The story itself is going to highlight these things, showing the Prince how widely varied the different Housedoms are and how they can so differently implement the same system (spirit of law vs letter of law, Freedom vs Order, Public servant vs ruler, etc).
Again, I feel it would be very hard to create believable "systems of people" and then tack on magic in a world in which all human interaction with non-human reality is based on magic. Systems of people are based on relationships and expectations and entitlements - all of which are going to have a magical component in your world. That would be like (actually worse than) creating the Dragaeran Empire without the Orb and without the Cycle and without the Gods - and then adding magic. It is a lot more believable to this spectator that all or most political solutions will include a direct magical component.
Havent read that one, but I think you misunderstand my intent. I am not trying to slap a magic system on top, Im trying to interweave them. I just want it to be a system that people built, and so follows some sort of reasonable human logic (otherwise I can have the characters reasonably debate its pros and cons). What I am trying to avoid is a system wherethe King rules because some God said so, and the Houses are their because they have always been, or because the magic system makes it unavoidable or some such. It needs to be a system that everyone is attached to enough to preserve, so tyrants dont just try to topple the whole thing, but also something is not so divinely mandated that the MC cant come along and make massive changes when the time comes. It need to be a system with human logic behind it, so that human logic can argue both for change and for maintaining the status quo.