Please elaborate.

So I'm getting that "Weapon hits flesh" sound and not the "bonk!" since the bandit is extremely strong and deals a lot of damage? Not because the weapon does hit my head instead of my shield?
I'm still confused about armor rating in general (what do those numbers really stand for), but that's probably stuff for another topic.
If you are getting the weapon hits flesh sound, then it probably means the block was not successful. I've notices this myself with weapons with wide sweep like two handed hammer or a troll sideswipe. They hit you from the side and if you are blocking the front, the shield misses.
Each armor rating point is worth 0.12% of damage. Plus there is hidden armor of 100 points if you wear any armor. With 230 Armor rating + 100 hidden armor you are doing 330 * 0.12 = 39% damage reduction. Maximum damage reduction you can get is 80% when your armor rating is at 567 or higher, because .12% * 667 = 80%
Blocking reduces the damage before the damage reaches the armor. Maximum reduction you can get is 85% I think. I'm not so sure how to calculate the damage reduction exactly, but I think you are probably getting 50% reduction or so.
Normal sword bandit probably does 20 points of damage per hit, probably. The shield reduces it to 10, then the armor reduces to 6. If you block, If your health is at 250, then the bandit has to hit you 40 times to kill you if you are blocking. You also regenerate meanwhile, so longer. They are not much of threat to you.
I noticed that a bandit boss with two-handed weapon can kill you with 3 or 4 power hits. If that's the case that means his normal damage output is 50 per hit and power attack is 100 per hit, which is fairly reasonable damage output from a skilled 2-handed opponent. If the opponent's damage output is 100, you are taking 30 points of damage even if you block successfully. If you miss your block, 60 points. So, against opponents who has high damage, it's often not a good idea to stand there and block. It's better to move back and dodge.