One thing that bother me is casting spells if you have 2-H weapon in your hands. The game don't let you cast spell because your hands are in use but I think that you can hold weapon with one hand and cast a spell. I don't say fight with one hand but just hold the weapon while you cast the spell. In example: wizard with staff in his hands. He can just hold his staff in one hand and cast with another.
And with cleric you should enable his spellcasting while he have weapon and shield, because he is divine caster not arcane and divine casters don't have complex motion with hands to cast a spell.
And another thing that would be useful is weapon sets. So that you don't have to manage your inventory every time you want to change weapon.
If you don't plan to improve KotC 1, this could surely be nice things to implement in KotC2
EDIT
I forgot.
Merry Christmas and happy new year to everyone