One of the most disapointing things in The Elder Scrolls franchise is how magic never makes use of any implement like Orbs, Grimoires, Staves, Wands, Rods, etc. Staves are essentially port-a-spell guns and their interaction with your own skill is fairly ridiculous (you get more charges out of something that doesn't train your skills, wew)
Considering how both melee and stealth has gear progression to increase their power, it would make sense that magic would see the same with Iron, Steel, Silver, Orcish, Elven and Daedric implements dictating the actual magnitude of your spells or at least acting as a multiplier, or at the very least reducing the mana used for each school depending on the implement.
This is the very basic start, equipment. A wizard can cast spells with just his hands but using the right implement can bring many advantages besides what it actually is.
Wands are excelent for projectile spells, they channel those easily, reducing the mana required and improving your aim. They can also unleash a small blast of mana for a very simple projectile.
Staves are excelent fall back weapons with good defensive capabilities but they also channel area effects very easily.
Grimories are held with your offhand and their magic presence lets you cast bigger spells in a shorter amount of time while also doubling as your spellbook.
Orbs are mana batteries that can spend from that first before draining you and excel at boosting spells that surround you, especially defensive ones.
Rods are mana batteries too but inferior to orbs, they can however be made from different materials so they are attuned to a specific type of creatures and summoning them is much easier. They are also a mace.
You have your equipment, next is your spellbook. Sadly most games don't even bother with this, only exception I can think of is Dungeon Siege 2.
Each magic word, rune, symbol and every spell takes space and it can either be memorized by you up to a limit set by your own mind or it can be written in a spellbook as many times as you want.
A proper wizard will memorize several offensive spells, a few tactical and utility ones and save space for a few runes in case he has to improvise and make a few changes on the fly.
But longer rituals or more specialized runes\spells will be written in spellbooks he keeps in his bag for when the situation demanding.
So for instance, a battlemage arrives at a castle where every door is locked with a different ward, he won't remenber every different combination to beat it since his mind is filled with different formulas for fireballs with different colors, but he has 3 spellbooks detailing lock and unlock spells and another with a few rituals to teleport back home.
Finnaly, you have the spell making itself. Spells are a sentence written in a language using runes or words, depending on what language is chosen. The combination matters a lot and so does the language (write in elvish and you get a mana discount, write in dwarvish and you get a bigger bang).
There are several symbols\runes for the same meaning but some express it better and thus are more powerfull, however you need an high intelect to understand what they actually mean.
Wizards can begin their career by joining a guild or a school where they are given access to basic spellbooks full of runes and explanations as to what they mean, after which they can write their own spells and enlarge their arsenal. However the more powerfull words are locked and kept secret by powerfull mages and you have to earn it from them. Or you can delve into abandoned dungeons and find tomes where those words show up, then you can spend a lot of time meditating on them and learn their meaning so you can finnaly use them.
So the player has progression in equipment, getting implements that better channel his spell but also in knowledge has he expands his collection of runes and spells, all requiring interacting with the world or exploring it.
I suppose sorcerers just begin by expelling fire from their hands, the amount expelled increasing the more they do it until they finnaly explode and an elemental takes their place, or something.
