Choosing magic items can be harder than it seems. I prefer to build armies around units, and then spend spare points on magic items.
The General: Taking a magic sword is probably the best option here. I would not recommend giving the Blade of Leaping Gold to a Vampire Lord unless you want people refusing to fight you. Something that enhances the General's magic powers can be useful too. For example, the Book of Nagash will raise him a level, but it is expensive at 100 points. If you prefer a defensive option, try going for the Black Amulet. it can give your opponent a nasty suprise when his tooled up General killer gets six wounds rebounded onto him!