That being said, I think doing without health potions keeps the combat fluent. Take the example of Assassin's Creed and Condemned. The combat in those games are quite dangerous, in that every time you take a hit you lose a lot of health. To avoid being hit, you must carefully place your blocks and attacks. So basically, there are a lot of blocks and few successful hits. I used to suggest this system but received the following criticism:
1. Combat becoming boring if the opponent keeps blocking your attacks.
2. Difficulty is too high because you die much easier.
But most agree that this combat mode is more fun than just take a sword and keep smashing trigger button. So how do we find a middle ground so that each successful hit means more and makes the player feel more successful, and yet doesn't drag the battle on forever, and with moderate difficulty?
In addition, there should be a feinting ability for the player. For example, when you click a mouse button to attack, if you press the button and release before the swing animation completes, your swing will be canceled, but the enemy has a probability to accidentally place a block. At this moment you can press the button and wait until the swing animation completes before releasing, creating a real swing attack (maybe a double click for power attack?), and then the enemy will miss the block timing and get hit.
However, health potion can still be used, maybe to speed up the regeneration speed for a period of time, in case you are surrounded by several enemies.
P.S. on a side note, when you played oblivion, do you remember clicking the attack button twice quickly within the same swing animation caused a second swing animation when you really didn't want it? I think it's somewhat annoying sometimes. but if you have to hold the button to complete a swing attack, then this issue can be eliminated.