I don't play much WFB but I've been looking at the different armies for a while and VC was one I was interested in, so here goes.
As far as I know, Skeletons are just an enormous mob of models meant to drown the enemy in bodies and attacks. Quantity over quality. Spears would probably be the best but I doubt shields will improve their survivability enough to be worth it.
Thats my impressions, but someone with more VC knowledge would be able to elaborate.