Make sure you're fully healed and...energy-d? before the fight. Do you mean you're going into that fight without Blast? Probably out of luck then. The "right" way to fix it would be to start from an earlier save and manage your items better. But if you're feeling impatient and have the Charm, use that to disable the hypno for the fight, which should help considerably. That said, I'm not sure that fight is winnable without Blast. My gut says probably, but you'll have to make several attempts with the charm on.