You can try to keep your people spread out to avoid multiple people getting hit by the summon and away from velius. If i remember correctly, you fight Wiegraf first then Velius. If that's the case then you could try to break his equipment and build up your characters with yell or talk skills. Another thing you could try is to afflict your characters with "Innocent" status using talk skills and that should make them immune to his Cyclops summon. If they're all innocent then you could play keep away while jumping and throwing things at him until he dies. Good idea about keeping ramza with a gun though, you definately need to keep him away from Velius. Hopelfully that will be at least a little bit helpful.