I guess I'm talking about two different things, without a clear delineation between them.
My primary focus is how hits are detected; eif someone walks up to you, hits their attack button, but their sword hits your shield, you won't be harmed. Or if you hold your own sword up and block it. Or if they do hit your armor, but it's only a light slash, then your armor's probably going to absorb that too. Compare that to typical MMORPG combat, where you could punch someone bare-fisted in full plate armor and the combat system will still let you do damage to them, because armor and weapons/fists just don't work in a realistic fashion. (ignore the possibility that you are a monk class where you actually have the ability to punch through armor)
TTK (time to kill, i.e. are there one hit kills or what) is a secondary issue. Of course it's not fun to be one hit killed, but if someone had to beat your shield out of your hand and then you get one hit killed, it's not the same as someone walking up to you and killing you in one swipe.
Well, in ESO it is like so:
You aim the Crosshair at your opponent (only needs to be roughly in that direction, this is no FPS) you then attack with weapon (either using a skill or doing a light or heavy attack - there is no auto attack in the game). If the defender does nothing to react, the damage is mitigated only by his armor (up to 50% if full on kitted out as a tank...very unlikely in PvP as you sacrifice a lot for that)
If the target reacts and holds up his block, he then loses stamina but reduces the damage by 50% (less stamina is spent and more damage is reduced if using an actual shield) it is then further reduced by the actual armor mitigation. Alternatively they could roll to Dodge, this would use up a larger portion of Stamina but result in no damage taken.
Damage of skills, light attacks etc. are all dictated by 'Weapon Damage' or 'Spell Damage' and to a lesser extent, your maximum resource pools. So, someone attempting to hit an oppoenent with their fists would do ignorable damage because an actual weapon provides a large portion of weapon/spell damage, if the opponent also blocked, it would be so low your natural regen would likely heal over it.
It is not as complex as what you are looking for, though likely as complex as you will likely see - there is no active 'removing the shield to stab your opponent' however, the effect can be similar - an opponent that blocks can only do so while he has Stamina, so rapid attacks will drain his stamina and once he gets low you can use hard hitting attacks to take them down. Alternatively, you can use various CC effects to attempt to prevent them from blocking (such as Fear, Stuns etc.) it takes time for them to Break Free of such effects which leaves them vulnerable, even better, Breaking Free costs a lot of Stamina which results in them running down faster.
Depending on build, an unsuspecting player can be taken down within two hits when surprised from stealth, on the flipside a fight could take several minutes if the players are skilled. So TTK can go from instant to long depending on build set ups and player skill.