[Nil]

I'm a warrior and not a DK, but I'll go ahead and chime in that I haven't seen much use for a shield so far - but I'm only level 15. Also, I have not yet come across a (edit: nice) shield.

Currently dual-wielding, I hold aggro better than with sword and board and I don't die much faster (especially considering that the critter dies faster as well). I do still use my defensive stance - not sure if you have something similar or not.

I had a DK in my party last weekend that tanked very, very well with a 2h axe (he was 2 levels higher than me, but the mobs were still red to him).

I'm sure this changes somewhat at high levels with very nice shields, but so far, they're pointless.