the hp doesn't always go up when you do that. sometimes it raises just vitality instead. If your weapons are too strong, then you should be fine. If you still need to raise your hp, then use magic. It will raise the points for that spell, use up mp so maybe that'll raise, and will take care of hp. The other thing you can do, is go to mysidia and get swap magic. bring it to the area with goblins, hornets, leg eaters, etc. and swap with them. It'll drop your hp to about 6 if it hits. Just make sure you have the gold for swap magic.