Concepts----------------------------
----Modular magic------------
It has been implied in the game that each thing as specific magical properties (such as a coccoon having the properties of lightness and expansion), and this has allowed peetu to create a "cage" by modifying a shield spell to emphisize ingredients that hinder movement (and this cage broke by being tampered with the expansion effects of a cocoon in the ingredients).
Likewise, the words in spells seem to be more than merely random (#kularzufrill and #frillyar both involve arrows, and both have "frill" in them).
What if there was a way to mix and match spell words and ingredients to create various custom effects (and many spectacular backfires).
Just imagine it...someone casts #flaryar and either it starts raining fire...or the spell does something entirely unexpected (such as exploding in the casters face) because those words were not meant to be paired together.
Could make spell research a real thing in-game. Throw in the fact that various combinations require various ingredients and/or magic skill to pull off that is hard to know in advance, and I think it would make for an interesting game dynamic.
Also applicable to custom potions too.
(to make it fair, you could have book items and labs where NPCs have already tried to experiment, giving people hints as to what works and what doesn't).
---Focus extensions-------------------
These are like...a modification of an existing focus, or perhaps a focus that requires a certain proficiency in another focus to obtain in the first place. Think "skill tree".
For example, you have astral soul, but from there you have the option to evolve that into something that emphisizes one school of magic much more at the expense of the others.
This could also be required in order to proceed beyond lvl 2 magic, and the only way to continue growing in a school (by specializing and focusing your efforts on one in particular).
An example of this might be...if you choose to specialize in life magic. You still have the spells of the lvl 2 magics, but you can now learn lvl 3 life magic (at the expense of not being able to learn lvl 3 war magic, for example).
Perhaps this concept can start general (such as the division of direct and indirect), and continue getting more specific (some schools could be naturally paired together, such as astral and nature, but eventually you gotta pick one).
---Expodiential magic levels------------------
I think the going trope that is a good idea is that magic is expodientially more powerful with each level of magic.
Level 1 magic isn't really all that impressive, and does not cut it for serious gameplay.
Level 2 magic is, obviously, what we use, and is considered sufficient, and sometimes even overpowered.
Level 3 magic should be to level 2 magic what level 2 magic is to level one magic. Balanced by difficulty of use, of course. Or the forced specialization idea mentioned above (where the higher up you go to learn magic, the more you have to specialize, to the point that at the top tier, you may only have one top-level spell at your disposal).
Level 4 should be much better than level 3, and so on.
----Spell stuff---------
Spells that do harm through physical hurts (like stone or ice spikes, or frillyar and chiza*) should do physical damage based on M attack, not magic damage or "earth damage" whatever that is supposed to be. What is "earth damage" supposed to be anyway?
*Chiza might be an exception if the damage is coming from a magic energy surrounding the blade rather than from the blade itself; it makes sense that the blade would just be a base for the magic energy to latch onto.
-----non-mage stuff---------
Wow, with all these possibilities in the field of magic, it doesn't make archery or swordfighting terribly interesting by comparison, does it?
Gotta think of interesting things to give the physical fighters.
How about...a focus that improves the drop rate of loot based on the characters luck stat? It would both make luck-based characters interesting and would cost the focus slot to use.
Though now that I think of it, why not have evolving focuses for warriors and archers too?
QUESTS!-------------------------------
A few quest ideas, but the general idea is as the player becomes more and more powerful, he is able to (and is put in the position to be responsible about) participate in quests about much more serious things, including (pardon the cliche) things that threaten the world itself.
So far the worst that players can face is a couple of witches trying to steal their soul to raise an undead army.
Ideas are:
-Preventing the incarnation of an outer god into the universe (or on the dark path, facilitating it).
-Actually fighting (or serving) incarnations of malignant entities of unimaginable power.
-quests to ascend to a level beyond the limit when you hit the level cap. Perhaps something like "god tier"?
-not actually remembering a lot of ideas here

Items--------------------------
Digested foodstuff - dropped by slime +50 HP; lampshade on how slimes drop perfectly edible foods.
"This 'food' was found inside a slime. You don't know what it used to be, and even though you just pulled it out of a slime, you are going to eat it anyway, aren't you? You are disgusting."
Charcoal - a less efficient alternative to coal using logs. Requires twice (or three times) as many to produce the same things as coal, and costs money to burn the logs into charcoal.
Weapons----------------------
-----------staves--------------
I think that mage weapons should be things that modify how spells work more than anything else. Such as by enhancing spells, reducing spell cost, or enabling spells that would otherwise not be castable. (do note that if the item completely eliminates the cost of spell ingredients, then the spell awards no magic exp)
Grand root - waives the requirement of having a root to summon something. In addition (maybe), the standard attack is replaced by a way to order your summons to attack the monster you are targetting.
Flare stick - This wand allows you to charge sulfur powders into it, using them to replace the standard attack with flar blasts. The flar blasts still cost sulfur, but this weapon eliminates the need to cast a spell in mid-battle.
Firebelch - This device uses sulfur powder to let loose a flowing stream of flar blasts. The device is highly inefficient, but the stream of fire it produces cuts through most monsters quickly.
Druids arm - this branch ripped from the druid tree contains nature magic, bent against it's origional purpose. Allows spells that root an enemy in place, inflict poison, or other such things.
Elder rod - this disturbing construction was made from the skin and bones of an ancient dark mage. It allows one to animate fire skulls with a skull, a dark crystal and some sulfur powder. It also allows one to summon a dark spirit that manifests from the dust on the ground, but this is much weaker. Finally, it allows you to summon a dark guardian that is temporarily grafted to you, and takes damage on your behalf (maybe it attacks independantly too? I don't know).
------------Other-----------------
Crystal Knife - Not very strong on it's own, but acts as an inexaustable spell component for chiza.
Parrying dagger (shield) - this "shield" is a knife that is used as an off-hand weapon to catch an opponents weapon. +5 attack, +5 defense, +5 dodge, +5 accuracy
Warding lantern (shield) - this jack-o-lantern doesn't stop physical attacks at all, but it does soak up incredible amounts of magic. Essentially an anti-magic shield.
Ether blade - This sword allows normal attacks to do magic damage instead of physical. Does not require any knowledge of magic to use.
whatever bow (make up new names that are better than the tacky ones I come up with) - A bow that, although not powerful, creates it's arrows out of the ambient magic around you. You never need to buy arrows for it.
Thats all I care to type for now; may add more later. H0nk.