For Skyrim, I think the shield system should be revamped so that it damages you fatigue to block things instead of your health.
Two main reasons:
1. It adds to the realism- you aren't going to die from blocking attacks over and over, you would just get worn out to the point where you couldn't lift it anymore, exposing you to the more damaging attacks.
2. It would help make fatigue something worth caring about- I never ran out of fatigue in Oblivion, and for the most part, it didn't affect gameplay at all. Having the blocking system damage fatigue will make players actually pay attention to it, and make combat more dynamic.
In regards to mages, the magical shield should be reworked. Instead of casting a spell that reduced damage for a certain time period, I think it would be cool to have to equip it to you left hand and cast it when you would normally block with a shield, which would still require a sense of timing. Instead of damaging fatigue however, the magical shield would take away from magika instead.
What are your thoughts?