Equip Ramza with a Chameleon Robe. Should be able to buy from Dorter around the beginning of chapter three iirc. As Lightning Stab or whatever it's called on PSP/iOS is actually Holy based damage, he flat out will not cast it as it would top your health off completely. He'll stick to just cheesing you with Earth Slash. If you have Hamedo/First Strike learned with a Blood Sword equipped, you pretty much won't even go below 100 HP. Keep your distance and keep spamming Accumulate until your AP is through the roof so you can hopefully do enough damage to Velius once your backup comes.