Skyrim's combat system and character progression could be infinitely improved if they were to offer "true Perks" combined with "true Skill trees". I think part of the problem is the fact that Perks are labeled after a specific skill, Archery, One-Hand etc, instead of playstyles. For example, the tree would be split as thus:
Warrior (General advancement tree for Warrior skills and abilities) - splits to 4 branches - Fighter (1H + Shield), Berserker (Dual-Wield), Crusader (2H), Archer (Archery)
Thief - "
Mage - "
This allows you to basically combine classes so you could theoretically combine Fighter & Wizard = Spellsword, or Crusader & Cleric = Paladin. The difference between the old system and the new is that you can specialize with your character a LOT more than you can now.
The "Perks" would be adjusted to being like more like Fallout's Perk system and would be your "modifiers" as the Skill tree has all of the specialization, abilities, and spells in it.

). It`s like you are born in August so you`re a Leo (if you believe that kind of thing) - It`s set. You can`t suddenly decide later you`re a Capricorn!