such as "upgrade alchemy effects."then you can see 3 instead of 2.so each skill that you use you get to choose a special perk(or upgrade a perk.)in that area that you have practiced in.but it gets more complicated.
you can choose blade perks such as "a special leg swing that has a chance to break enemys legs or "special power attack that has a chance to paralyze an enemy"then after that you could upgrade that perk by making it more likely to parlyze the enemy when hit by the enemy or simply choose another blade perk.
so you have a overall blade perk.then there is another layer to the blade skill were there could be spescific weapon perks - katanas,claymores,shortswords ect.so you could choose 10% more damage for your katana.then you could do 20% more damage for your katana or 10% more slashing speed for it. so as you progress in blade you can choose spescific perks depending on your weapon type. the same could be with speechcraft.
you could consitrate on intimidating the npc or you could make him laugh.with smithing you could be a good repair well.or you could upgrade your weapons.so you can specilize in spescific things while still having thoughs overall perks like using less repair hammers.
with alchemy you could be good at poisions,or you could make a good healing potion.or you could make good illusion potions like detect life or chameleon potoins.
okay so thats the skill system, but the third layer would be the attributes.which you can upgrade every time you level up.so if you use a blade alot then upgrade your strength.in other words attributes would be there to bring in leveling,while perks are gained when you use and practice with skills.
so just to make it clear there would be magic, so when you get better at magic you choose a magic perk.and under that are all the magic types,so if you use destruction alot when u get better at it you choose a destruction perk (or an ilusion,restoration ect.)
now for somethings like sneak would be much more difficult. but my idea of solving this would be you could choose your sneak perk.then choose pickpocketing perks,ranged sneak attack perks or melee sneak attacks.but what about lockpicking?well...iam not quite sure..or some skills could not hav a 2nd level at all,but iam not going to go there yet. ill update it when i figure this out.so in my opinion this a great leveling system if it is refined.i spent alot of time and thought on this so get the disscusion going!what is your take on leveling and how do u like mine?and what skills would have a problem with this system?keep it a civil