You say you have two swords? Well hopefully you have a save file just outside of this battle, that will help. Anyways I would suggest using battle skill for Ramza. Use power break on him, and since you have two swords, he will do 2 power breaks, you should hit with at least 1 of them. This will lower Wiegraf's attack significantly. If blade grasp doesn't protect against his lightning stab, I would suggest stocking up on X-potions, and using auto potion.