Kraco actually did, but I'll add my own theories into this as well. Perhaps Glasses only has the ability to launch a certain number of attacks at a time, within certain areas. Also I'm guessing that Giselle(sp) is attacking from another location (a form of teleporting a piece of itself onto the battlefield), so piercing the dimensional barrier probably takes a certain amount of time. Maybe the shadows need to be nearly black in order for Giselle to attack. My guess for the multiple weapons at the same time is that it takes concentration on Glasses' part in order to use the weapons/attacks.