Obviously, if this guy "died multiple times", he saved before Wiegraf and can't go back. So, avoiding suggestions relating to buying stuff, do this:

Have someone be a summoner, use the jp trick and master the class (though you only need Lich here). So, one of your dudes has Lich. This summon takes off half Velius's HP.

Make Ramza a Ninja, Lancer, Samurai, or something both durable and strong. If you use the Lancer, make sure to do the jp trick and master it. If you have accumulate/yell, that makes the battle much easier, if not (not many people do their first time through).

Use the ability trick and master a time mage, for Haste.

Master a chemist with the ability trick and have auto potion, x potion, and pheonix down. Drop all regular potions.

The 4th character is up to you, if you have Agris built up, that'd be great, if not, oh well.

Just keep trying different mixes until you find one that works- sometime its just luck of what the enemies do.