Shield block is expensive and I think most people would agree that using a shield in PvP unless you are a shield dedicant paladin isn't usually the best option. A thief needs to kill quickly so dual wielding is almost always the better option. Most importantly the cost is what, 10 thief points? That is a lot for something that you shouldn't be using except in maybe specific situations.

I'd scrap lock picking abilities if you plan to focus on PK as well.

I believe climb lets you get into Arial city. Don't know about anything else. I'd imagine the trail around Hamsah and the snow wurm lair are probably places it comes in handy as well.