As for tanking, forget it. That's an MMO teamplay mechanic that has little place in role playing games.
really? Ever played for example Dragon Age?
Yep, one of the better CRPGs from the last few years. I don't like that they used taunting/threat/tanking mechanics there either.
It is something that originated with MMOs and I'd have loved for it to stay there - the tanking mechanism is based on AI opponents that act like idiots in any given situation rather than trying to perform as well as they can given their available abilities.
This results in extremely predictable behaviour from the AI, which is quite nice when the real challenge is coordinating different people performing the same encounter (or type of encounter) multiple times, and something I've had great fun with in MMOs...
...but is is the sort of simplified "I only have to protect these guys and not look out to protect the rest of the party, because the AI only attacks those I want it to" gameplay that provides little tactical challenge (and seems bloody difficult to justify unless the opposition is described as insane), which is why you'll not find it in traditional pen-and-paper or computer roleplaying games. (Where you'll find things such as defensive spells being important for personal survival and attacks of opportunity and obstacles important tactical tools for protecting weaker party members)
And whats the point in a shield skill?
For the one using shields to be better protected when using a shield, something that a player may or may not find useful depending on how often the character in question comes under attack, which (in this game), will depend a lot on the players' tactical skills at setting up AOO zones and environmental hazards, and (in this game) on the 1H v 2H damageoutput.
Given the huge difference in damageoutput between 1H and 2H and how strong healing magic is, I find using a sword and board setup hard to justify in the current game-balance, but that's a balance discussion, not a "what is the point in the skill".
