like...
crafting (smithing, whatever you want to call it)
- plate
- hide
- weapon
Speech
- Mercantile
- Persuasion
- intimidation
marksman
-Bow
-crossbow
-throwing
conjuration
-necromany
-daedra-mancy?
-bounding
(obviously better names to be found)
Lockpicking
- lock type A
- Lock type B
- Lock type C
- trap probing
Alchemy
-potions/poisons
-explosives
-cooking? (as you can tell, i dont mean things to be final. perhaps bethesda might seperate potions and poisons)
Languages (the subskills doing most of the work) (shouldnt contribute to leveling) (perhaps each language could be unlocked from quests and stay hidden until then?)
- dragon
- Daedric beast (daedroth, clanfear, scamps might use it)
- whatever's appropriate
hand to hand
-grabbing
-striking
acrobatics
- slow (climbing up high ledges, natural surfaces, rope etc)
- fast (vaulting, wall running, precision jumping)
- dodge (rolling on fall, diving/rolling out of the way of danger etc)
You can pretty much think of every skill's subsets. Not so much pickpocketing.
Anyways i also propose a sort of web idea
Using one handed axes makes you better with axes (including two handed axes) and one handed weapons
using warhammers makes you better with maces and two handed weapons
using glaives makes you better with spears and two handed weapons. (using one handed spears would probably not realy help using a sword though, would it? )
This would mean that whilst you arent skilled with daggers (or warhammers in skyrims case) because you use a claymore you still have skill with claymores if you use a longsword and you can still use a mace well if you are a decent swordsman!