Skeleton warriors. Seriously. I find that WoC players often equip these guys with great weapons to save points, since they're confident that they won't be killed before they get to strike (and for good reason).
However it ALSO means that their mounts get to hit before they do. So charge in and challenge with the champion (or accept the challenge which he has to make). Horse gets two attacks hitting on 3s wounding on 3s which will probably kill the skeleton. Lord/hero doesn't get to attack. He loses combat 1 point to 5 (charge, banner, 3 ranks). Watch him fail that LD5 break test and run him down.
Skeleton champions are the best damned 10 points you'll ever spend
Edit: As for your vampire lord, you want him AS FAR AWAY AS POSSIBLE from this dude. Red Fury is wasted on models who don't take wounds, and 3++ rerolling 1s is a tough nut to crack. Plus he hits back at S7 and you've only got a 4++. Far better accepting the challenge with your unit champion and trying to beat him on combat res. Blender vamps want to be killing rank-and-file for ACR not banging their heads against a wall of impenetrable defenses.
Chaos lords are about the best character for killing other characters. Vampire lords are about the best at killing RnF and netting you CR. And then there are daemon princes....
To the OP, mounting your vamp and sticking him in a unit will not make him die of crumble. The unit should take that damage. It will take away his LoS! Roll though, I believe. Same with if he has flying and joins bats, etc he will have no LoS! Can I get a rule check on that @The Sun King ?
Also I think great weapons were designed with goblin heroes in mind. Otherwise your points in quick blood are wasted counter-acting the ASL from a great weapon. Plus vamps have high Int and are likely to score rerolls when they have ASF. If I took a great weapon on a vamp I might pair it with dread knight and beguile + AoDM and use him as a semi-cheap challenger.