I got an idea for two more types of runes/infusions:
Runes and infusions of skill, and of mastery.
Runes/infusions of skill temporarily raise a skill value when activated.
duration, amount of skill boosted, cooldown etc. can vary, ofcourse.
examples:
"Rune of Illuminate"
Use mode: Activated
Range: melee/personal
Cooldown: 35
Travel speed: Instantaneous
Usage: 1 turn
Description: Activate the rune to boost your effectiveness of the Illuminate spell by 2 points for 10 turns
"Infusion of Health" (personally, I wouldn't let this one take up a slot, it would be a waste of space)
Use mode: Activated
Range: melee/personal
Cooldown: 40
Travel speed: Instantaneous
Usage: Instant
Description: Activate the rune to boost the effectiveness of the Health skill by 1 point for 15 turns
However, if I could find 2 of those variants of aforementioned infusion of Health, I might just equip them for permanent health gain

"Infusion of Health"
Use mode: Activated
Range: melee/personal
Cooldown: 30 turns
Travel speed: instantaneous
Usage: Instant
Description: Activate the rune to boost the effectiveness of the Health skill by 4 points for 20 turns
Runes would be used for the 'magic' skills, infusions would be used for the non-magic skills, to not mess with antimagic quests and stuff.
In the lower level dungeons, you will only be able to find infusions/runes for skills at the beginning of talent trees.
Runes/infusions boosting skills further down the talent trees can be found in higher-level dungeons.
Runes of mastery are of a whole different level. These should be extremely rare, and finding them will be a real prize.
Here's what they do:
Once applied on the body, these runes/infusions have a passive effect:
They raise the mastery level of a talent tree.
Again, runes of mastery for magically-inclined skills
Infusions of mastery for non-magically inclined skills.
Examples:
"Rune of Cunning mastery: Shadow Magic"
Use mode: Passive
Range: Melee/personal
Description:
When applied to the body, this rune grants the wearer a bonus of +0.20 to his mastery of Cunning: Shadow Magic
"Infusion of Cunning mastery: Survival"
Use mode: Passive
Range: Melee/personal
Description: When applied to the body, this infusion grants the wearer a bonus of +0.10 to his mastery of Cunning: Survival
EDIT: Forgot to mention that none of these runes/infusions grant the user control over a new skill(set). Only skill(s) already posessed by a character are affected.